AU2012203465B2 - A method to produce an immunoglobulin preparation with improved yield - Google Patents

Abstract

The present invention provides improved methods for the manufacturing of IVIG products. These methods offer various advantages such as reduced loss of IgG during purification and improved quality of final products. In other aspects, the present invention provides aqueous and pharmaceutical compositions suitable for intravenous, subcutaneous, and/or intramuscular administration. In yet other embodiments, the present invention provides methods of treating a disease or condition comprising administration of an IgG composition provided herein.

Description

1 Regulation 3.2 AUSTRALIA 5 Patents Act 1990 10 15 COMPLETE SPECIFICATION 20 STANDARD PATENT 25 30 APPLICANT: Baxter International Inc & Baxter Healthcare S.A. Invention Title: A METHOD TO PRODUCE AN IMMUNOGLOBULIN PREPARATION WITH IMPROVED YIELD 35 The following statement is a full description of this invention, including the best method of performing it known to me: 40 2 A METHOD TO PRODUCE AN IMMUNOGLOBULIN PREPARATION WITH IMPROVED YIELD BACKGROUND OF THE INVENTION 5 Immune globulin products from human plasma were first used in 1952 to treat immune deficiency. Initially, intramuscular or subcutaneous administration of Immunoglobulin isotype G (IgG) were the methods of choice. For injecting larger amounts of IgG necessary for effective treatment of various diseases, however, the intravenous administrable products with lower concentrated IgG (50mg/mL) were developed. 10 Usually intravenous immunoglobulin (IVIG), contains the pooled immunoglobulin G (IgG) immunoglobulins from the plasma of more than a thousand blood donors. Typically containing more than 95% unmodified IgG, which has intact Fc-dependent effector functions, and only trace amounts of immunoglobulin A (IgA) or immunoglobulin M (IgM), IVIGs are sterile, purified IgG products primarily used in 15 treating three main categories of medical conditions: (1) immune deficiencies such as X linked agammaglobulinemia, hypogammaglobulinemia (primary immune deficiencies), and acquired compromised immunity conditions (secondary immune deficiencies), featuring low antibody levels; (2) inflammatory and autoimmune diseases; and (3) acute infections. 20 Specifically, many people with primary immunodeficiency disorders lack antibodies needed to resist infection. In certain cases these deficiencies can be supplemented by the infusion of purified IgG, commonly through intravenous administration (i.e., IVIG therapy). Several primary immunodeficiency disorders are commonly treated in the fashion, including X-linked Agammaglobulinemia (XLA), Common Variable 25 Immunodeficiency (CVID), Hyper-IgM Syndrome (HIM), Severe Combined Immunodeficiency (SCID), and some IgG subclass deficiencies (Blaese and Winkelstein, J. Patient & Family Handbook for Primary Immunodeficiency Diseases. Towson, MD: Immune Deficiency Foundation; 2007). While IVIG treatment can be very effective for managing primary immunodeficiency 30 disorders, this therapy is only a temporary replacement for antibodies that are not being produced in the body, rather than a cure for the disease. Accordingly, patients dependent upon IVIG therapy require repeated doses, typically about once a month for life. This 3 need places a great demand on the continued production of IVIG compositions. However, unlike other biologics that are produced via in vitro expression of recombinant DNA vectors, IVIG is fractionated from human blood and plasma donations. Thus, IVIG products cannot be increased by simply increasing the volume of production. Rather the 5 level of commercially available IVIG is limited by the available supply of blood and plasma donations. Several factors drive the demand for IVIG, including the acceptance of IVIG treatments, the identification of additional indications for which IVIG therapy is effective, and increasing patient diagnosis and IVIG prescription. Notably, the global demand for IVIG 10 has more than quadrupled since 1990 and continues to increase today at an annual rate between about 7% and 10% (Robert P., Pharmaceutical Policy and Law, 11 (2009) 359 367). For example, the Australian National Blood Authority reported that the demand for IVIG in Australia grew by 10.6% for the 2008-2009 fiscal year (National Blood Authority Australia Annual Report 2008-2009). 15 Due in part to the increasing global demand and fluctuations in the available supply of immunoglobulin products, several countries, including Australia and England, have implemented demand management programs to protect supplies of these products for the highest demand patients during times of product shortages. It has been reported that in 2007, 26.5 million liters of plasma were fractionated, 20 generating 75.2 metric tons of IVIG, with an average production yield of 2.8 grams per liter (Robert P., supra). This same report estimated that global IVIG yields are expected to increase to about 3.43 grams per liter by 2012. However, due to the continued growth in global demand for IVIG, projected at between about 7% and 13% annually between now and 2015, further improvement of the overall IVIG yield will be needed to meet 25 global demand. A number of IVIG preparation methods are used by commercial suppliers of IVIG products. One common problem with the current IVIG production methods is the substantial loss of IgG during the purification process, estimated to be more than 35% of the total IgG content of the starting material. One challenge is to maintain the quality of 30 viral inactivation and lack of impurities which can cause adverse reactions, while bolstering the yield of IgG. At the current production levels of IVIG, what may be considered small increases in the yield are in fact highly significant. For example at 4 2007 production levels, a 2% increase in efficiency, equal to an additional 56 milligrams per liter, would generate 1.5 additional metric tons of IVIG. In the fourth installment of a series of seminal papers published on the preparation and properties of serum and plasma proteins, Cohn et al. (J Am. Chem. Soc., 1946, 68(3): 5 459-475) first described a methods for the alcohol fractionation of plasma proteins (method 6), which allows for the isolation of a fraction enriched in IgG from human plasma. Several years later, Oncley et al. (J Am. Chem. Soc., 1949, 71(2): 541-550) expanded upon the Cohn methods by publishing a method (method 9) that resulted in the isolation of a purer IgG preparation. 10 These methods, while laying the foundation for an entire industry of plasma derived blood factors, were unable to provide IgG preparations having sufficiently high concentrations for the treatment of several immune-related diseases, including Kawasaki syndrome, immune thrombocytopenic purpura, and primary immune deficiencies. As such, additional methodologies employing various techniques, such as ion exchange 15 chromatography, were developed to provide higher purity and higher concentration IgG formulations. Hoppe et al. (Munch Med Wochenschr 1967 (34): 1749-1752) and Falksveden (Swedish Patent No. 348942) and Falksveden and Lundblad (Methods of Plasma Protein Fractionation 1980) were among the first to employ ion exchange chromatography for this purpose. 20 Various modem methods employ a precipitation step, such as caprylate precipitation (Lebing et al., Vox Sang 2003 (84):193-201) and Cohn Fraction (I+)II+III ethanol precipitation (Tanaka et al., Braz JMed Biol Res 2000 (33)37-30) coupled to column chromatography. Most recently, Teschner et al. (Vox Sang, 2007 (92):42-55) have described a method for production of a 10% IVIG product in which cryo-precipitate is 25 first removed from pooled plasma and then a modified Cohn-Oncley cold ethanol fractionation is performed, followed by S/D treatment of the intermediate, ion exchange chromatography, nanofiltration, and optionally ultrafiltration/diafiltration. However, despite the improved purity, safety, and yield afforded by these IgG manufacturing methods, a significant amount of IgG is still lost during the purification 30 process. For example, Teschner et al. report that their method results in an increased IgG yield of 65% (Teschner et al., supra). This represents a loss of about a third of the IgG present in the pooled plasma fraction during the manufacturing process. Given the 5 average global IVIG yield per liter plasma processed, manufacturing processes used by other commercial providers of IVIG likely result in significantly higher IgG losses. As such, a need exists for improved and more efficient methods for manufacturing IVIG products. The present invention satisfies these and other needs by providing IVIG 5 manufacturing methods that produce yields that are at least 6 to 10% higher than currently achievable, as well as IVIG compositions provided there from. BRIEF SUMMARY OF THE INVENTION In one aspect, the present invention provides methods for preparing an enriched IgG compositions (e.g., IVIG compositions) from plasma. Advantageously, the methods 10 provided herein provide significant improvements over current state of the art manufacturing methods for preparing IVIG compositions. For example, the methods provided herein allow for increased yields of IgG in the final bulk composition without losing the purity required for intravenous administration. In one aspect, a method is provided for preparing an enriched IgG composition from 15 plasma comprising the steps of (a) precipitating a cryo-poor plasma fraction, in a first precipitation step, with between about 6% and about 10% alcohol at a pH of between about 7.0 and about 7.5 to obtain a first precipitate and a first supernatant, (b) precipitating IgG from the first supernatant, in a second precipitation step, with between about 20% and about 25% alcohol at a pH of between about 6.7 and about 7.3 to form a 20 second precipitate, (c) re-suspending the second precipitate to form a suspension, (d) precipitating IgG from the suspension formed in step (c), in a third precipitation step, with between about 22% and about 28% alcohol at a pH of between about 6.7 and about 7.3 to form a third precipitate, (e) re-suspending the third precipitate to form a suspension, and (f) separating the soluble fraction from the suspension formed in step (e), 25 thereby forming an enriched IgG composition, wherein at least one of the first precipitation step, second precipitation step, or third precipitation step comprises spray addition of the alcohol. In one embodiment, alcohol is added in the first precipitation step by spraying. In another embodiment, alcohol is added in the second precipitation step by spraying. In yet another embodiment, alcohol is added in the third precipitation 30 step by spraying. In certain embodiments, the pH of one or more solution may be adjusted by the addition of a pH modifying agent by spraying. In related embodiments, the pH of at least one of 6 the first precipitation step, second precipitation step, or third precipitation step is achieved by addition of a pH modifying solution after addition of the alcohol, or before and after the addition of alcohol, during and after the addition of alcohol, or before, during, and after the addition of alcohol. In yet another related embodiment, the pH of a 5 precipitation step may be maintained for the entirety of the precipitation reaction by continuously adjusting the pH. In one specific embodiment, the pH of the first precipitation step is adjusted after the addition of alcohol by spray addition of a pH modifying agent. In another embodiment, the pH of the second precipitation step is adjusted after the addition of alcohol by spray 10 addition of a pH modifying agent. In yet another embodiment, the pH of the third precipitation step is adjusted after the addition of alcohol by spray addition of a pH modifying agent. Additionally, the preparatory methods provided herein may further comprise an ion exchange chromatography step (i.e., anion exchange and/or cation exchange 15 chromatography), a nanofiltration step, an ultrafiltration/diafiltration step, or any other suitable purification technique to further enhance the purity or quality of the IVIG preparations. In another aspect, a method is provided for preparing an enriched IgG composition from plasma comprising the steps of adjusting the pH of a cryo-poor plasma fraction to at or 20 about 7.0, (b) adjusting the ethanol concentration of the cryo-poor plasma fraction of step (a) to at or about 25% (v/v) at a temperature between at or about -7C and at or about 9'C, thereby forming a mixture, (c) separating liquid and precipitate from the mixture of step (b), (d) re-suspending the precipitate of step (c) with a buffer containing phosphate and acetate, wherein the pH of the buffer is adjusted with at or about 600 ml of glacial 25 acetic acid per 1000L of buffer, thereby forming a suspension, (e) mixing finely divided silicon dioxide (SiO 2 ) with the suspension from step (d) for at least about 30 minutes, (f) filtering the suspension with a filter press, thereby forming a filtrate, (g) washing the filter press with at least 3 filter press dead volumes of a buffer containing phosphate and acetate, wherein the pH of the buffer is adjusted with at or about 150 ml of glacial acetic 30 acid per 1000L of buffer, thereby forming a wash solution, (h) combining the filtrate of step (f) with the wash solution of step (g), thereby forming a solution, and treating the solution with a detergent, (i) adjusting the pH of the solution of step (h) to at or about 7.0 7 and adding ethanol to a final concentration of at or about 25%, thereby forming a precipitate, (j) separating liquid and precipitate from the mixture of step (i), (k) dissolving the precipitate in an aqueous solution comprising a solvent or detergent and maintaining the solution for at least 60 minutes, (1) passing the solution after step (k) 5 through a cation exchange chromatography column and eluting proteins absorbed on the column in an eluate, (m) passing the eluate from step (1) through an anion exchange chromatography column to generate an effluent, (n) passing the effluent from step (m) through a nanofilter to generate a nanofiltrate, (o) passing the nanofiltrate from step (n) through an ultrafiltration membrane to generate an ultrafiltrate; and (p) diafiltrating the 10 ultrafiltrate from step (o) against a diafiltration buffer to generate a diafiltrate having a protein concentration between about 8% (w/v) and about 12% (w/v), thereby obtaining a composition of concentrated IgG. In another aspect, the present invention provides aqueous IgG compositions prepared by the methods described herein. Generally, the IgG compositions have high purity (e.g., at 15 least 95%, 98%, 99%, or higher IgG contents), contain protein concentrations between about 20 g/L and about 200 g/L, and contain extremely low levels of common IVIG contaminants, such as IgG, IgM, Fibrinogen, Transferrin, ACA, amidolytic activity, PKA, and the like. In yet another aspect, pharmaceutical IgG compositions and formulations suitable for use 20 in IVIG therapies are provided. The pharmaceutical formulations have high purity (e.g., at least 98%, 99%, or higher IgG contents), contain protein concentrations between about 20 g/L and about 200 g/L, and contain extremely low levels of common IVIG contaminants, such as IgG, IgM, Fibrinogen, Transferrin, ACA, amidolytic activity, PKA, and the like. Generally, the pharmaceutical compositions are appropriately 25 formulated for intravenous administration (i.e., for IVIG therapy), subcutaneous administration, or intramuscular administration. In another aspect, the present invention provides methods for treating an immunodeficiency, autoimmune disease, or acute infection in a human in need thereof, the method comprising administering a pharmaceutical composition described herein. 30 Non, limiting examples of diseases and conditions that may be treated or managed through the methods provided herein include, allogeneic bone marrow transplant, chronic lymphocytic leukemia, idiopathic thrombocytopenic purpura (ITP), pediatric HIV, 8 primary immunodeficiencies, Kawasaki disease, chronic inflammatory demyelinating polyneuropathy (CIDP), kidney transplant with a high antibody recipient or with an ABO incompatible donor, chronic fatigue syndrome, clostridium difficile colitis, dermatomyositis and polymyositis, Graves' ophthalmopathy, Guillain-Barr6 syndrome, 5 muscular dystrophy, inclusion body myositis, Lambert-Eaton syndrome, Lupus erythematosus, multifocal motor neuropathy, multiple sclerosis (MS), myasthenia gravis, neonatal alloimmune thrombocytopenia, Parvovirus B 19 infection, pemphigus, post transfusion purpura, renal transplant rejection, spontaneous Abortion/Miscarriage, stiff person syndrome, opsoclonus Myoclonus, severe sepsis and septic shock in critically ill 10 adults, toxic epidermal necrolysis, chronic lymphocytic leukemia, multiple myeloma, X linked agammaglobulinemia, hypogammaglobulinemia, primary immune deficiency, RRMS, Alzheimer's disease, and Parkinson's disease. BRIEF DESCRIPTION OF THE DRAWINGS 15 Figure 1: IgG concentration as determined by ELISA (A) and nephelometric (0) methods and total protein concentration (m) present in the Fraction 11+111 filtrate wash as a function of the number of dead volumes of buffer used to wash the filtration device post-filtration. Figure 2: Average PKA activity in Precipitate G dissolved fractions after extraction and 20 clarification at pH 3.8 to 5.0 by addition of acetic acid in the presence and absence of Aerosil (silicon dioxide) treatment. Figure 3: Average fibrinogen content in Precipitate G dissolved fractions after extraction and clarification at pH 3.8 to 5.0 by addition of acetic acid in the presence and absence of Aerosil (silicon dioxide) treatment. 25 Figure 4: Average amidolytic activity in Precipitate G dissolved fractions after extraction and clarification at pH 3.8 to 5.0 by addition of acetic acid in the presence and absence of Aerosil (silicon dioxide) treatment. Figure 5: Amidolytic activity in Precipitate G dissolved fractions extracted and clarified at pH 3.8 to 7.8 after incubation for two weeks at 4C (+) or for an additional week at 30 room temperature (m).

9 Figure 6: PKA activity in Precipitate G dissolved fractions extracted and clarified at pH 3.8 to 7.8. Figure 7: Difference in purity of the modified fraction 11+111 filtrate with and without fumed silica treatment. Chromatograph of cellulose acetate electrophoresis of modified 5 fraction 11+111 filtrate (A) clarified by filter aid only and (B) clarified after fumed silica treatment. DEFINITIONS Throughout this specification and the claims, unless the context requires otherwise, the 10 word "comprise" and its variations, such as "comprises" and "comprising," will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. As used herein, an "antibody" refers to a polypeptide substantially encoded by an immunoglobulin gene or immunoglobulin genes, or fragments thereof, which specifically 15 bind and recognize an analyte (antigen). The recognized immunoglobulin genes include the kappa, lambda, alpha, gamma, delta, epsilon and mu constant region genes, as well as the myriad immunoglobulin variable region genes. Light chains are classified as either kappa or lambda. Heavy chains are classified as gamma, mu, alpha, delta, or epsilon, which in turn define the immunoglobulin classes, IgG, IgM, IgA, IgD, and IgE, 20 respectively. An exemplary immunoglobulin (antibody) structural unit is composed of two pairs of polypeptide chains, each pair having one "light" (about 25 kD) and one "heavy" chain (about 50-70 kD). The N-terminus of each chain defines a variable region of about 100 to 110 or more amino acids primarily responsible for antigen recognition. The terms 25 variable light chain (VL) and variable heavy chain (VH) refer to these light and heavy chains respectively. As used herein, the term "ultrafiltration (UF)" encompasses a variety of membrane filtration methods in which hydrostatic pressure forces a liquid against a semi-permeable membrane. Suspended solids and solutes of high molecular weight are retained, while 30 water and low molecular weight solutes pass through the membrane. This separation process is often used for purifying and concentrating macromolecular (103 - 106 Da) 10 solutions, especially protein solutions. A number of ultrafiltration membranes are available depending on the size of the molecules they retain. Ultrafiltration is typically characterized by a membrane pore size between 1 and 1000 kDa and operating pressures between 0.01 and 10 bar, and is particularly useful for separating colloids like proteins 5 from small molecules like sugars and salts. As used herein, the term "diafiltration" is performed with the same membranes as ultrafiltration and is a tangential flow filtration. During diafiltration, buffer is introduced into the recycle tank while filtrate is removed from the unit operation. In processes where the product is in the retentate (for example IgG), diafiltration washes components out of 10 the product pool into the filtrate, thereby exchanging buffers and reducing the concentration of undesirable species. As used herein, the term "about" denotes an approximate range of plus or minus 10% from a specified value. For instance, the language "about 20%" encompasses a range of 18-22%. 15 As used herein, the term "mixing" describes an act of causing equal distribution of two or more distinct compounds or substances in a solution or suspension by any form of agitation. Complete equal distribution of all ingredients in a solution or suspension is not required as a result of "mixing" as the term is used in this application. As used herein, the term "solvent" encompasses any liquid substance capable of 20 dissolving or dispersing one or more other substances. A solvent may be inorganic in nature, such as water, or it may be an organic liquid, such as ethanol, acetone, methyl acetate, ethyl acetate, hexane, petrol ether, etc. As used in the term "solvent detergent treatment," solvent denotes an organic solvent (e.g., tri-N-butyl phosphate), which is part of the solvent detergent mixture used to inactivate lipid-enveloped viruses in solution. 25 As used herein, the term "detergent" is used in this application interchangeably with the term "surfactant" or "surface acting agent." Surfactants are typically organic compounds that are amphiphilic, i.e., containing both hydrophobic groups ("tails") and hydrophilic groups ("heads"), which render surfactants soluble in both organic solvents and water. A surfactant can be classified by the presence of formally charged groups in its head. A 30 non-ionic surfactant has no charge groups in its head, whereas an ionic surfactant carries a net charge in its head. A zwitterionic surfactant contains a head with two oppositely charged groups. Some examples of common surfactants include: Anionic (based on 11 sulfate, sulfonate or carboxylate anions): perfluorooctanoate (PFOA or PFO), perfluorooctanesulfonate (PFOS), sodium dodecyl sulfate (SDS), ammonium lauryl sulfate, and other alkyl sulfate salts, sodium laureth sulfate (also known as sodium lauryl ether sulfate, or SLES), alkyl benzene sulfonate; cationic (based on quaternary 5 ammonium cations): cetyl trimethylammonium bromide (CTAB) a.k.a. hexadecyl trimethyl ammonium bromide, and other alkyltrimethylammonium salts, cetylpyridinium chloride (CPC), polyethoxylated tallow amine (POEA), benzalkonium chloride (BAC), benzethonium chloride (BZT); Long chain fatty acids and their salts: including caprylate, caprylic acid, heptanoat, hexanoic acid, heptanoic acid, nanoic acid, decanoic acid, and 10 the like; Zwitterionic (amphoteric): dodecyl betaine; cocamidopropyl betaine; coco ampho glycinate; nonionic: alkyl poly(ethylene oxide), alkylphenol poly(ethylene oxide), copolymers of poly(ethylene oxide) and poly(propylene oxide) (commercially known as Poloxamers or Poloxamines), alkyl polyglucosides, including octyl glucoside, decyl maltoside, fatty alcohols (e.g., cetyl alcohol and oleyl alcohol), cocamide MEA, 15 cocamide DEA, polysorbates (Tween 20, Tween 80, etc.), Triton detergents, and dodecyl dimethylamine oxide. As used herein, the term "Intravenous IgG" or "IVIG" treatment refers generally to a therapeutic method of intravenously, subcutaneously, or intramuscularly administering a composition of IgG immunoglubulins to a patient for treating a number of conditions 20 such as immune deficiencies, inflammatory diseases, and autoimmune diseases. The IgG immunoglobulins are typically pooled and prepared from plasma. Whole antibodies or fragments can be used. IgG immunoglobulins can be formulated in higher concentrations (e.g., greater than 10%) for subcutaneous administration, or formulated for intramuscular administration. This is particularly common for specialty IgG preparations which are 25 prepared with higher than average titres for specific antigens (e.g., Rho D factor, pertussis toxin, tetanus toxin, botulism toxin, rabies, etc.). For ease of discussion, such subcutaneously or intramuscularly formulated IgG compositions are also included in the term "IVIG" in this By "therapeutically effective amount or dose" or "sufficient/effective amount or dose," it 30 is meant a dose that produces effects for which it is administered. The exact dose will depend on the purpose of the treatment, and will be ascertainable by one skilled in the art using known techniques (see, e.g., Lieberman, Pharmaceutical Dosage Forms (vols. 1-3, 1992); Lloyd, The Art, Science and Technology ofPharmaceutical Compounding (1999); 12 Pickar, Dosage Calculations (1999); and Remington: The Science and Practice of Pharmacy, 20th Edition, 2003, Gennaro, Ed., Lippincott, Williams & Wilkins). As used in this application, the term "spraying" refers to a means of delivering a liquid substance into a system, e.g., during an alcohol precipitation step, such as a modified 5 Cohn fractionation I or 11+111 precipitation step, in the form of fine droplets or mist of the liquid substance. Spraying may be achieved by any pressurized device, such as a container (e.g., a spray bottle), that has a spray head or a nozzle and is operated manually or automatically to generate a fine mist from a liquid. Typically, spraying is performed while the system receiving the liquid substance is continuously stirred or otherwise 10 mixed to ensure rapid and equal distribution of the liquid within the system. DETAILED DESCRIPTION OF THE INVENTION I. Overview As routinely practiced in modem medicine, sterilized preparations of concentrated immunoglobulins (especially IgGs) are used for treating medical conditions that fall into 15 three main classes: immune deficiencies, inflammatory and autoimmune diseases, and acute infections. One commonly used IgG product, intravenous immunoglobulin or IVIG, is formulated for intravenous administration, for example, at a concentration of at or about 10% IgG. Concentrated immunoglobulins may also be formulated for subcutaneous or intramuscular administration, for example, at a concentration at or about 20 20% IgG. For ease of discussion, such subcutaneously or intramuscularly formulated IgG compositions are also included in the term "IVIG" in this application. In certain aspects, the present invention provides methods for IVIG manufacture that increase the final yield of the product, yet still provide IVIG compositions of equal or higher quality and in some cases higher concentrations. In one embodiment, the present 25 invention provides modified Cohn fractionation methods that reduce IgG loss at one or more precipitation steps. In another aspect, the present invention provides IgG compositions prepared according to the improved manufacturing methods provided herein. Advantageously, these compositions are less expensive to prepare than commercial products currently available 30 due to the improved yield afforded by the methods provided herein. Furthermore, these compositions are as pure, if not more pure, than compositions manufactured using 13 commercial methods. Importantly, these compositions are suitable for use in IVIG therapy for immune deficiencies, inflammatory and autoimmune diseases, and acute infections. In one embodiment, the IgG composition is at or about 10% IgG for intravenous administration. In another embodiment, the IgG composition is at or about 5 20% for subcutaneous or intramuscular administration. In another aspect, the present invention provides pharmaceutical compositions and formulations of IgG compositions prepared according to the improved manufacturing methodologies provided herein. In certain embodiments, these compositions and formulations provide improved properties as compared to other IVIG compositions 10 currently on the market. For example, in certain embodiments, the compositions and formulations provided herein are stable for an extended period of time. In yet another aspect, the present invention provides method for treating immune deficiencies, inflammatory and autoimmune diseases, and acute infections comprising the administration of an IgG composition prepared using the improved methods provided 15 herein. II. Methods of IVIG Manufacture Generally, immunoglobulin preparations according to the present invention can be prepared from any suitable starting materials, for example, recovered plasma or source plasma. In a typical example, blood or plasma is collected from healthy donors. Usually, 20 the blood is collected from the same species of animal as the subject to which the immunoglobulin preparation will be administered (typically referred to as "homologous" immunoglobulins). The immunoglobulins are isolated from the blood by suitable procedures, such as, for example, precipitation (alcohol fractionation or polyethylene glycol fractionation), chromatographic methods (ion exchange chromatography, affinity 25 chromatography, immunoaffinity chromatography, etc.) ultracentrifugation, and electrophoretic preparation, and the like. (See, e.g., Cohn et al., J. Am. Chem. Soc. 68:459-75 (1946); Oncley et al., J Am. Chem. Soc. 71:541-50 (1949); Barundern et al., Vox Sang. 7:157-74 (1962); Koblet et al., Vox Sang. 13:93-102 (1967); U.S. Patent Nos. 5,122,373 and 5,177,194; the disclosures of which are hereby incorporated by reference 30 in their entireties for all purposes).

14 In many cases, immunoglobulins are prepared from gamma globulin-containing products produced by alcohol fractionation and/or ion exchange and affinity chromatography methods well known to those skilled in the art. For example, purified Cohn Fraction II is commonly used as a starting point for the isolation of immunoglobulins. The starting 5 Cohn Fraction II paste is typically about 95 percent IgG and is comprised of the four IgG subtypes. The different subtypes are present in Fraction II in approximately the same ratio as they are found in the pooled human plasma from which they are obtained. The Fraction II is further purified before formulation into an administrable product. For example, the Fraction II paste can be dissolved in a cold purified aqueous alcohol 10 solution and impurities removed via precipitation and filtration. Following the final filtration, the immunoglobulin suspension can be dialyzed or diafiltered (e.g., using ultrafiltration membranes having a nominal molecular weight limit of less than or equal to 100,000 daltons) to remove the alcohol. The solution can be concentrated or diluted to obtain the desired protein concentration and can be further purified by techniques well 15 known to those skilled in the art. Furthermore, additional preparative steps can be used to enrich a particular isotype or subtype of immunoglobulin. For example, protein A, protein G or protein H sepharose chromatography can be used to enrich a mixture of immunoglobulins for IgG, or for specific IgG subtypes. See generally Harlow and Lane, Using Antibodies, Cold Spring 20 Harbor Laboratory Press (1999); Harlow and Lane, Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory Press (1988); and U.S. Patent No. 5,180,810, the disclosures of which are hereby incorporated by reference in their entireties for all purposes. Unlike the methods described above, in one aspect the present invention provides 25 methods of preparing concentrated IgG compositions that utilize a cryo-poor starting material. Generally, the methods provided herein utilize both modified Cohn-Oncley alcohol fractionation steps and ion exchange chromatography to provide superior IgG yields, while maintaining the same, if not improved, quality as found in currently available commercial IVIG preparations. For example, in certain embodiments methods 30 are provided that yield a final bulk IgG composition containing close to 75% of the IgG content found in the raw plasma starting material. These methods represent at least a 10% to 12% increase in the overall IgG yield over existing state of the art purification methods. For example, it is estimated that the GAMMAGARD* LIQUID manufacturing 15 process provide a final yield of between about 60% and 65% of the IgG content found in the starting material. As such, the methods provided herein provide a significant improvement over the existing IgG purification technologies. In one embodiment, the present invention provides a purified IgG composition that 5 contains at least 70% of the IgG content found in the raw plasma starting material. In another embodiment, a purified IgG composition is provided that contains at least 75% of the IgG content found in the raw plasma starting material. In other embodiments, a purified IgG composition provided herein will contain at least about 65% of the IgG content found in the raw plasma starting material, or at least 66%, 67%, 68%, 69%, 70%, 10 71%, 72%73%, 74%, 75%, or more of the IgG content found in the raw plasma starting material. A. Modified Alcohol Precipitation/Ion Exchange Chromatography Fractionation Methods 15 In one aspect, the present invention provides improved methods for the manufacture of IgG compositions suitable for use in IVIG therapy. Generally, these methods provide IgG preparations having higher yields and comparable if not higher purity than current methods employed for the production of commercial IVIG products. In one specific aspect, the present invention provides a method for preparing a 20 composition of concentrated IgG from plasma, e.g., 10% IVIG, the method comprising performing at least one alcohol precipitation step and at least one ion exchange chromatography step. In particular, several steps in the improved upstream process are different from prior processes, e.g., the use of 25% ethanol at lower temperatures, ethanol addition by spraying, pH adjustment by spraying, and the use of finely divided silica 25 particles. In a certain embodiment, the method comprises the steps of (a) precipitating a cryo-poor plasmid fraction, in a first precipitation step, with between about 6% and about 10% alcohol at a pH of between about 6.7 and about 7.3 to obtain a supernatant enriched in IgG, (b) precipitating IgG from the supernatant with between about 20% and about 30% 30 alcohol at a lower temperature and at a pH of between about 6.7 and about 7.3 to form a first precipitate, (c) re-suspending the first precipitate formed in step (b) to form a 16 suspension, (d) treating the suspension formed in step (c) with a detergent, (e) precipitating IgG from the suspension with between about 20% and about 30% alcohol at a pH of between about 6.7 and about 7.3 to form a second precipitate, (f) re-suspending the second precipitate formed in step (e) to form a suspension, (g) treating the suspension 5 formed in step (f) with a solvent and/or detergent, and (h) performing at least one ion exchange chromatography fractionation thereby preparing a composition of concentrated IgG. In one embodiment, the method further comprises treating the suspension formed in step (c) with finely divided silica dioxide (SiO 2 ) and filtering the solution prior to step (d). 10 In one embodiment, a method for preparing a concentrated IgG composition from plasma is provided, the method comprising the steps of (a) adjusting the pH of a cryo-poor plasma fraction to about 7.0, (b) adjusting the ethanol concentration of the cryo-poor plasma fraction of step (a) to at or about 25% (v/v) at a temperature between about -5 0 C and about -9'C, thereby forming a mixture, wherein the ethanol concentration may be 15 adjusted by spraying, (c) separating liquid and precipitate from the mixture of step (b), (d) re-suspending the precipitate of step (c) with a buffer containing phosphate and acetate, wherein the pH of the buffer is adjusted with at or about 600 ml of glacial acetic acid per 1000L of buffer, thereby forming a suspension, (e) mixing finely divided silicon dioxide (SiO2) with the suspension from step (d) for at least about 30 minutes, (f) 20 filtering the suspension with a filter press, thereby forming a filtrate, (g) washing the filter press with at least 3 filter press dead volumes of a buffer containing phosphate and acetate, wherein the pH of the buffer is adjusted with about 150 ml of glacial acetic acid per 1000L of buffer, thereby forming a wash solution, (h) combining the filtrate of step (f) with the wash solution of step (g), thereby forming a solution, and treating the 25 solution with a detergent, (i) adjusting the pH of the solution of step (h) to about 7.0 and adding ethanol to a final concentration of at or about 25%, thereby forming a precipitate, wherein the ethanol concentration and/or pH may be adjusted by spraying (j) separating liquid and precipitate from the mixture of step (i), (k) dissolving the precipitate in an aqueous solution comprising a solvent or detergent and maintaining the solution for at 30 least 60 minutes, (1) passing the solution after step (k) through a cation exchange chromatography column and eluting proteins absorbed on the column in an eluate, (in) passing the eluate from step (1) through an anion exchange chromatography column to generate an effluent (i.e., flow-through), (n) passing the effluent from step (in) through a 17 nanofilter to generate a nanofiltrate, (o) passing the nanofiltrate from step (n) through an ultrafiltration membrane to generate an ultrafiltrate, and (p) diafiltrating the ultrafiltrate from step (o) against a diafiltration buffer to generate a diafiltrate having a protein concentration between about 8% (w/v) and about 22% (w/v), thereby obtaining a 5 composition of concentrated IgG. In one embodiment, the temperature of step (b) is at or about -7C. In certain embodiments, the diafiltrate will have a protein concentration between about 8% and about 12%, for example, about 8%, or about 9%, 10%, 11%, or 12%. In a preferred embodiment, the diafiltrate will have a protein concentration of at or about 10 10%. In another preferred embodiment, the diafiltrate will have a protein concentration of at or about 11%. In yet another preferred embodiment, the diafiltrate will have a protein concentration of at or about 12%. In other embodiments, the diafiltrate will have a protein concentration between about 13% and about 17%, for example, about 13%, or about 14%, 15%, 16%, or 17%. In yet other embodiments, the diafiltrate will have a 15 protein concentration between about 18% and about 22%, for example, about 18%, or about 19%, 20%, 21%, or 22%. In a preferred embodiment, the diafiltrate will have a protein concentration of at or about 20%. In another preferred embodiment, the diafiltrate will have a protein concentration of at or about 21%. In yet another preferred embodiment, the diafiltrate will have a protein concentration of at or about 22%. 20 In certain embodiments of the present invention, the methods provided herein may comprise improvements in two or more of the fractionation process steps described above. For example, embodiments may include improvements in the first precipitation step, the Modified Fraction 11+111 precipitation step, the Modified Fraction 11+111 dissolution step, and/or the Modified Fraction II+III suspension filtration step. 25 In one embodiment, the improvement made in the first precipitation step is the addition of alcohol by spraying. In another embodiment, the improvement made in the first precipitation step is the addition of a pH modifying agent by spraying. In yet embodiment, the improvement made in the first precipitation step is the adjustment of the pH of the solution after addition of the alcohol. In a related embodiment, the 30 improvement made in the first precipitation step is the maintenance of the pH during the addition of the alcohol. In another related embodiment, the improvement made in the first precipitation step is the maintenance of the pH during the precipitation incubation 18 time by continuously adjusting the pH of the solution. In certain embodiments, the first precipitation step may be improved by implementing more than one of these improvements. Further improvements that may be realized in this step will be evident from the section provided below discussing the first precipitation step - Modified 5 Fractionation I. By implementing one or more of the improvements described above, a reduced amount of IgG is lost in the precipitate fraction of the first precipitation step and/or a reduced fraction of IgG is irreversibly denatured during the precipitation step. In one embodiment, the improvement made in the Modified Fraction 11+111 precipitation step is the addition of alcohol by spraying. In another embodiment, the improvement 10 made in the Modified Fraction 11+111 precipitation step is the addition of a pH modifying agent by spraying. In yet embodiment, the improvement made in the Modified Fraction 11+111 precipitation step is the adjustment of the pH of the solution after addition of the alcohol. In a related embodiment, the improvement made in the Modified Fraction 11+111 precipitation step is the maintenance of the pH during the addition of the alcohol. In 15 another related embodiment, the improvement made in the Modified Fraction 11+111 precipitation step is the maintenance of the pH during the precipitation incubation time by continuously adjusting the pH of the solution. In another aspect, the Modified Fraction 11+111 precipitation step is improved by increasing the concentration of alcohol to at or about 25%. In yet another embodiment, the Modified Fraction 11+111 20 precipitation step is improved by lowering the incubation temperature to between about 7C and -9'C. In certain embodiments, the Modified Fraction 11+111 precipitation step may be improved by implementing more than one of these improvements. Further improvements that may be realized in this step will be evident from the section provided below discussing the second precipitation step - Modified Fractionation 11+11.. By 25 implementing one or more of the improvements described above, a reduced amount of IgG is lost in the supernatant fraction of the Modified Fraction II+II precipitation step and/or a reduced fraction of IgG is irreversibly denatured during the precipitation step. In one embodiment, the improvement made in the Modified Fraction 11+111 dissolution step is achieved by increasing the glacial acetic acid content of the dissolution buffer to 30 about 0.06%. In another embodiment, the improvement made in the Modified Fraction 11+111 dissolution step is achieved by maintaining the pH of the solution during the dissolution incubation time by continuously adjusting the pH of the solution. In another embodiment, the improvement made in the Modified Fraction 11+111 dissolution step is 19 achieved by mixing finely divided silicon dioxide (SiO 2 ) with the Fraction 11+111 suspension prior to filtration. In certain embodiments, the Modified Fraction 11+111 dissolution step may be improved by implementing more than one of these improvements. Further improvements that may be realized in this step will be evident 5 from the section provided below discussing the Modified Fraction 11+111 dissolution step - Extraction of the Modified Fraction 11+111 Precipitate. By implementing one or more of the improvements described above, an increased amount of IgG is recovered in the Fraction 11+111 suspension and/or the amount of impurities is reduced in the Fraction 11+111 suspension. 10 An exemplary improvement made in the Modified Fraction 11+111 suspension filtration step is realized by post-washing the filter with at least about 3.6 dead volumes of dissolution buffer containing at or about 150 mL glacial acetic acid per 1000 L. Further improvements that may be realized in this step will be evident from the section provided below discussing the Modified Fraction 11+111 suspension filtration step - Pretreatment 15 and Filtration of the Modified Fraction 11+111 Suspension. By implementing one or more of the improvements described above, a reduced amount of IgG is lost during the Modified Fraction 11+111 suspension filtration step. In one embodiment, the method may comprise an improvement in the first precipitation step and the Modified Fraction 11+111 precipitation step. 20 In another embodiment, the method may comprise an improvement in the first precipitation step and the Modified Fraction 11+111 dissolution step. In another embodiment, the method may comprise an improvement in the first precipitation step and the Modified Fraction 11+111 suspension filtration step. In another embodiment, the method may comprise an improvement in the Modified 25 Fraction 11+111 precipitation step and the Modified Fraction 11+111 dissolution step. In another embodiment, the method may comprise an improvement in the Modified Fraction 11+111 precipitation step and the Modified Fraction 11+111 suspension filtration step. In another embodiment, the method may comprise an improvement in the Modified 30 Fraction 11+111 dissolution step and the Modified Fraction 11+111 suspension filtration step.

20 In another embodiment, the method may comprise an improvement in the first precipitation step, the Modified Fraction 11+111 precipitation step, and the Modified Fraction 11+111 dissolution step. In another embodiment, the method may comprise an improvement in the first 5 precipitation step, the Modified Fraction 11+111 precipitation step, and the Modified Fraction 11+111 suspension filtration step. In another embodiment, the method may comprise an improvement in the first precipitation step, the Modified Fraction 11+111 dissolution step, and the Modified Fraction 11+111 suspension filtration step. 10 In another embodiment, the method may comprise an improvement in the Modified Fraction 11+111 precipitation step, the Modified Fraction 11+111 dissolution step, and the Modified Fraction 11+111 suspension filtration step. In another embodiment, the method may comprise an improvement in all of the first precipitation step, the Modified Fraction 11+111 precipitation step, the Modified Fraction 15 11+111 dissolution step, and the Modified Fraction 11+111 suspension filtration step. In certain embodiments, one process improvement in the IgG purification methods provided herein comprises the spray addition of one or more solutions that would otherwise be introduced into a plasma fraction by fluent addition. For example, in certain embodiments the process improvement comprises the addition of alcohol (e.g., 20 ethanol) into a plasma fraction for the purposes of precipitation of one or more protein species by spraying. In other embodiments, solutions that may be added to a plasma fraction by spraying include, without limitation, a pH modifying solution, a solvent solution, a detergent solution, a dilution buffer, a conductivity modifying solution, and the like. In a preferred embodiment, one or more alcohol precipitation steps is performed 25 by the addition of alcohol to a plasma fraction by spraying. In a second preferred embodiment, one or more pH adjustment steps is performed by the addition of a pH modifying solution to a plasma fraction by spraying. In certain embodiments, another process improvement, which may be combined with any other process improvement, comprises the adjustment of the pH of a plasma fraction 30 being precipitated after and/or concomitant with the addition of the precipitating agent (e.g., alcohol or polyethelene glycol). In some embodiments, a process improvement is 21 provided in which the pH of a plasma fraction being actively precipitated is maintained throughout the entire precipitation incubation or hold step by continuous monitoring and adjustment of the pH. In preferred embodiments the adjustment of the pH is performed by the spray addition of a pH modifying solution. 5 In other embodiments, another process improvement, which may be combined with any other process improvement, comprises the use of a finely divided silica treatment step to remove impurities. 1. Preparation of Cryo-poor Plasma The starting material used for the preparation of concentrated IgG compositions generally 10 consists of either recovered plasma (i.e., plasma that has been separated from whole blood ex vivo) or source plasma (i.e., plasma collected via plasmapheresis). The purification process typically starts with thawing previously frozen pooled plasma, which has already been assayed for safety and quality considerations. Thawing is typically carried out at a temperature no higher than 6C. After complete thawing of the frozen 15 plasma at low temperature, centrifugation is performed in the cold (e.g., < 6 0 C) to separate solid cryo-precipitates from the liquid supernatant. Alternatively, the separation step can be performed by filtration rather than centrifugation. The liquid supernatant (also referred to as "cryo-poor plasma," after cold-insoluble proteins removed by centrifugation from fresh thawed plasma) is then processed in the next step. Various 20 additional steps can be taken at this juncture for the isolation of factor eight inhibitor bypass activity (FEIBA), Factor IX-complex, Factor VII-concentrate, or Antithrombin Ill-complex. 2. First Precipitation Event - Modified Fractionation I In this step, cryo-poor plasma is typically cooled to about 0 1 1 0 C and the pH is adjusted 25 to between about 7.0 and about 7.5, preferably between about 7.1 and about 7.3, most preferably about 7.2. In one embodiment, the pH of the cryo-poor plasma is adjusted to a pH of at or about 7.2. Pre-cooled ethanol is then added while the plasma is stirred to a target concentration of ethanol at or about 8% v/v. At the same time the temperature is further lowered to between about -4 and about 0 0 C. In a preferred embodiment, the 30 temperature is lowered to at or about -2'C, to precipitate contaminants such as a 2 macroglobulin, PIA- and P1c-globulin, fibrinogen, and Factor VIII. Typically, the 22 precipitation event will include a hold time of at least about 1 hour, although shorter or longer hold times may also be employed. Subsequently, the supernatant (Supernatant I), ideally containing the entirety of the IgG content present in the cryo-poor plasma, is then collected by centrifugation, filtration, or another suitable method. 5 As compared to conventional methods employed as a first fractionation step for cryo poor plasma (Cohn et al., supra; Oncley et al., supra), the present invention provides, in several embodiments, methods that result in improved IgG yields in the Supernatant I fraction. In one embodiment, the improved IgG yield is achieved by adding the alcohol by spraying. In another embodiment, the improved IgG yield is achieved by adding a pH 10 modifying agent by spraying. In yet another embodiment, the improved IgG yield is achieved by adjusting the pH of the solution after addition of the alcohol. In a related embodiment, the improved IgG yield is achieved by adjusting the pH of the solution during the addition of the alcohol. In one specific aspect, the improvement relates to a method in which a reduced amount of 15 IgG is lost in the precipitate fraction of the first precipitation step. For example, in certain embodiments, a reduced amount of IgG is lost in the precipitate fraction of the first precipitation step as compared to the amount of IgG lost in the first precipitation step of the Cohn method 6 protocol. In certain embodiments, the process improvement is realized by adjusting the pH of the 20 solution to between about 7.0 and about 7.5 after the addition of the precipitating alcohol. In other embodiments, the pH of the solution is adjusted to between about 7.1 and about 7.3 after addition of the precipitating alcohol. In yet other embodiments, the pH of the solution is adjusted to about 7.0 or about 7.1, 7.2, 7,3, 7.4, or 7.5 after addition of the precipitating alcohol. In a particular embodiment, the pH of the solution is adjusted to 25 about 7.2 after addition of the precipitating alcohol. As such, in certain embodiments, a reduced amount of IgG is lost in the precipitate fraction of the first precipitation step as compared to an analogous precipitation step in which the pH of the solution is adjusted prior to but not after addition of the precipitating alcohol. In one embodiment, the pH is maintained at the desired pH during the precipitation hold or incubation time by 30 continuously adjusting the pH of the solution. In one embodiment, the alcohol is ethanol. In other certain embodiments, the process improvement is realized by adding the precipitating alcohol and/or the solution used to adjust the pH by spraying, rather than by 23 fluent addition. As such, in certain embodiments, a reduced amount of IgG is lost in the precipitate fraction of the first precipitation step as compared to an analogous precipitation step in which the alcohol and/or solution used to adjust the pH is introduced by fluent addition. In one embodiment, the alcohol is ethanol. 5 In yet other certain embodiments, the improvement is realized by adjusting the pH of the solution to between about 7.0 and about 7.5. In a preferred embodiment, the pH of the solution is adjusted to between about 7.1 and about 7.3. In other embodiments, the pH of the solution is adjusted to at or about 7.0, 7.1, 7.2, 7.3, 7.4, or 7.5 after the addition of the precipitating alcohol and by adding the precipitating alcohol and/or the solution used to 10 adjust the pH by spraying, rather than by fluent addition. In a particular embodiment, the pH of the solution is adjusted to at or about 7.2 after addition of the precipitating alcohol and by adding the precipitating alcohol and/or the solution used to adjust the pH by spraying, rather than by fluent addition. In one embodiment, the alcohol is ethanol. 3. Second Precipitation Event - Modified Fractionation 11+111 15 To further enrich the IgG content and purity of the fractionation, Supernatant I is subjected to a second precipitation step, which is a modified Cohn-Oncley Fraction 11+111 fractionation. Generally, the pH of the solution is adjusted to a pH of between about 6.6 and about 6.8. In a preferred embodiment, the pH of the solution is adjusted to at or about 6.7. Alcohol, preferably ethanol, is then added to the solution while being stirred 20 to a final concentration of between about 20% and about 25% (v/v) to precipitate the IgG in the fraction. In a preferred embodiment, alcohol is added to a final concentration of at or about 25% (v/v) to precipitate the IgG in the fraction. Generally, contaminants such as ai-lipoprotein, ai-antitrypsin, Gc-globulins, aix-glycoprotin, haptoglobulin, ceruloplasmin, transferrin, hemopexin, a fraction of the Christmas factor, thyroxin 25 binding globulin, cholinesterase, hypertensinogen, and albumin will not be precipitated by these conditions. Prior to or concomitant with alcohol addition, the solution is further cooled to between about -7'C and about -9'C. In a preferred embodiment, the solution is cooled to a temperature at or about -7'C. After completion of the alcohol addition, the pH of the 30 solution is immediately adjusted to between about 6.8 and about 7.0. In a preferred embodiment, the pH of the solution is adjusted to at or about 6.9. Typically, the precipitation event will include a hold time of at least about 10 hours, although shorter or 24 longer hold times may also be employed. Subsequently, the precipitate (Modified Fraction 11+111), which ideally contains at least about 85%, preferably at least about 90%, more preferably at least about 95%, of the IgG content present in the cryo-poor plasma, is separated from the supernatant by centrifugation, filtration, or another suitable method 5 and collected. As compared to conventional methods employed as a second fractionation step for cryo-poor plasma (Cohn et al., supra; Oncley et al., supra), the present invention provides, in several embodiments, methods that result in improved IgG yields in the Modified Fraction 11+111 precipitate. In a related embodiment, the present invention provides methods that result in a reduced loss of IgG in the Modified 11+111 supernatant. 10 As compared to conventional methods employed as a second fractionation step for cryo poor plasma (Cohn et al., supra; Oncley et al., supra), the present invention provides, in several embodiments, methods that result in improved IgG yields in the Modified Fraction 11+111 precipitate. In one embodiment, the improvement is realized by the addition of alcohol by spraying. In another embodiment, the improvement is realized by 15 the addition of a pH modifying agent by spraying. In another embodiment, the improvement is realized by adjusting the pH of the solution after addition of the alcohol. In a related embodiment, the improvement is realized by adjusting the pH of the solution during addition of the alcohol. In another embodiment, the improvement is realized by increasing the concentration of alcohol (e.g., ethanol) to about 25% (v/v). In another 20 embodiment, the improvement is realized by lowering the temperature of the precipitation step to between about -7C and -9'C. In a preferred embodiment, the improvement is realized by increasing the concentration of alcohol (e.g., ethanol) to about 25% (v/v) and lowing the temperature to between about -7C and -9'C. In comparison, both Cohn et al. and Oncley et al. perform precipitation at -5'C and Oncley 25 et al. use 20% alcohol, in order to reduce the level of contaminants in the precipitate. Advantageously, the methods provided herein allow for maximal IgG yield without high levels of contamination in the final product. In one aspect, the improvement relates to a method in which a reduced amount of IgG is lost in the supernatant fraction of the modified Fraction 11+111 precipitation step. In 30 certain embodiments, the process improvement is realized by adjusting the pH of the solution to between about 6.7 and about 7.1 immediately after or during the addition of the precipitating alcohol. In another embodiment, the process improvement is realized by maintaining the pH of the solution to between about 6.7 and about 7.1 continuously 25 during the precipitation incubation period. In other embodiments, the pH of the solution is adjusted to between about 6.8 and about 7.0 immediately after or during the addition of the precipitating alcohol, or to a pH of about 6.7, 6.8, 6.9, 7.0, or 7.1 immediately after or during the addition of the precipitating alcohol. In a particular embodiment, the pH of 5 the solution is adjusted to about 6.9 immediately after or during the addition of the precipitating alcohol. In certain embodiments, the pH of the solution is maintained at between about 6.8 to about 7.0 continuously during the precipitation incubation period, or at a pH of about 6.9 continuously during the precipitation incubation period. As such, in certain embodiments, a reduced amount of IgG is lost in the supernatant fraction of the 10 second precipitation step as compared to an analogous precipitation step in which the pH of the solution is adjusted prior to but not after addition of the precipitating alcohol or to an analogous precipitation step in which the pH of the solution is not maintained during the entirety of the precipitation incubation period. In one embodiment, the pH is maintained at the desired pH during the precipitation hold or incubation time by 15 continuously adjusting the pH of the solution. In one embodiment, the alcohol is ethanol. In another embodiment, the process improvement is realized by adding the precipitating alcohol and/or the solution used to adjust the pH by spraying, rather than by fluent addition. As such, in certain embodiments, a reduced amount of IgG is lost in the supernatant fraction of the second precipitation step as compared to an analogous 20 precipitation step in which the alcohol and/or solution used to adjust the pH is introduced by fluent addition. In one embodiment, the alcohol is ethanol. In another embodiment, the process improvement is realized by performing the precipitation step at a temperature between about -7C and about -9'C. In one embodiment, the precipitation step is performed at a temperature of at or about -7C. In 25 another embodiment, the precipitation step is performed at a temperature of at or about 8'C. In another embodiment, the precipitation step is performed at a temperature of at or about -9'C. In certain embodiments, the alcohol concentration of the precipitation step is between about 23% and about 27%. In a preferred embodiment, the alcohol concentration is between about 24% and about 26%. In another preferred embodiment, 30 the alcohol concentration is at or about 25%. In other embodiments, the alcohol concentration may be at or about 23%, 24%, 25%, 26%, or 27%. In a particular embodiment, the second precipitation step is performed at a temperature of at or about - 26 7'C with an alcohol concentration of at or about 25%. In one embodiment, the alcohol is ethanol. The effect of increasing the alcohol concentration of the second precipitation from 20%, as used in Oncley et al., supra, to 25% and lowering the temperature of the incubation 5 from -5'C, as used in the Cohn and Oncley methods is a 5 %to 6% increase in the IgG content of the modified Fraction 11+111 precipitate. In another embodiment, the process improvement is realized by adjusting the pH of the solution to between about 6.7 and about 7.1, preferably at or about 6.9, immediately after or during the addition of the precipitating alcohol, maintaining the pH of the solution at a 10 pH of between about 6.7 and about 7.1, preferably at or about 6.9, by continuously adjusting the pH during the precipitation incubation period, and by adding the precipitating alcohol and/or the solution used to adjust the pH by spraying, rather than by fluent addition. In another particular embodiment, the process improvement is realized by performing the precipitation step at a temperature between about -7'C and about -9'C, 15 preferably at or about -7'C and by precipitating the IgG with an alcohol concentration of between about 23% and about 27%, preferably at or about 25%. In yet another particular embodiment, the process improvement is realized by incorporating all of the Modified Fraction 11+111 improvements provided above. 4. Extraction of the Modified Fraction 11+111 Precipitate 20 In order to solubilize the IgG content of the modified Fraction 11+111 precipitate, a cold extraction buffer is used to re-suspend the Fractionation 11+111 precipitate at a typical ratio of 1 part precipitate to 15 parts of extraction buffer. Other suitable re-suspension ratios may be used, for example from about 1:8 to about 1:30, or from about 1:10 to about 1:20, or from about 1:12 to about 1:18, or from about 1:13 to about 1:17, or from 25 about 1:14 to about 1:16. In certain embodiments, the re-suspension ratio may be about 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29, 1:30, or higher. Suitable solutions for the extraction of the modified 11+111 precipitate will generally have a pH between about 4.0 and about 5.5. In certain embodiments, the solution will have a 30 pH between about 4.5 and about 5.0, in other embodiments, the extraction solution will have a pH of about 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, or 27 5.5. In a preferred embodiment, the pH of the extraction buffer will be at or about 4.5. In another preferred embodiment, the pH of the extraction buffer will be at or about 4.7. In another preferred embodiment, the pH of the extraction buffer will be at or about 4.9. Generally, these pH requirements can be met using a buffering agent selected from, for 5 example, acetate, citrate, monobasic phosphate, dibasic phosphate, mixtures thereof, and the like. Suitable buffer concentrations typically range from about 5 to about 100 mM, or from about 10 to about 50 mM, or about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 mM buffering agent. The extraction buffer will preferably have a conductivity of from about 0.5 mS-cm- to 10 about 2.0 mS-cm'. For example, in certain embodiments, the conductivity of the extraction buffer will be about 0.5 mS cm 1 , or about 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or about 2.0 mS-cm 1 . One of ordinary skill in the art will know how to generate extraction buffers having an appropriate conductivity. In one particular embodiment, an exemplary extraction buffer may contain at or about 5 15 mM monobasic sodium phosphate and at or about 5 mM acetate at a pH of at or about 4.5 ± 0.2 and conductivity of at or about 0.7 to 0.9 mS/cm. Generally, the extraction is performed at between about 0 0 C and about 1 0 0 C, or between about 2'C and about 8'C. In certain embodiments, the extraction may be performed at about 0 0 C, 1 C, 2-C, 3 C, 4-C, 5 C, 6-C, 7'C, 8'C, 9'C, or 10 C. In a particular 20 embodiment, the extraction is performed at between about 2'C and about 10 C. Typically, the extraction process will proceed for between about 60 and about 300 minutes, or for between about 120 and 240 min, or for between about 150 and 210 minutes, while the suspension is continuously stirred. In certain embodiments, the extraction process will proceed for about 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 25 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or about 300 minutes. Advantageously, it has been found that compared to the current manufacturing process for GAMMAGARD* LIQUID (Baxter Healthcare), which employs an extraction buffer containing 5 mM monobasic sodium phosphate, 5 mM acetate, and 0.051% glacial acetic 30 acid (v/v), that by increasing the glacial acetic acid content to at or about 0.06% (v/v), a substantial increase in the yield increase in the final IgG composition can be obtained. As compared to methods previously employed for the extraction of the precipitate formed 28 by the second precipitation step (GAMMAGARD* LIQUID), the present invention provides, in several embodiments, methods that result in improved IgG yields in the Modified Fraction 11+111 suspension. In one aspect, the improvement relates to a method in which a reduced amount of IgG is 5 lost in the non-solubilized fraction of the Modified Fraction 11+111 precipitate. In one embodiment, the process improvement is realized by extracting the Modified Fraction 11+111 precipitate at a ratio of 1:15 (precipitate to buffer) with a solution containing 5 mM monobasic sodium phosphate, 5 mM acetate, and 0.06% glacial acetic acid (v/v). In another embodiment, the improvement is realized by maintaining the pH of the solution 10 during the duration of the extraction process. In another aspect, the improvement relates to a method in which an increased amount of IgG is solubilized from the Fraction 11+111 precipitate in the Fraction 11+111 dissolution step. In one embodiment, the process improvement is realized by solubilizing the Fraction 11+111 precipitate in a dissolution buffer containing 600 mL glacial acetic acid 15 per 1000 L. In another embodiment, the improvement relates to a method in which impurities are reduced after the IgG in the Fraction 11+11I precipitate is solubilized. In one embodiment, the process improvement is realized by mixing finely divided silicon dioxide (SiO 2 ) with the Fraction 11+111 suspension for at least about 30 minutes. 5. Pretreatment and Filtration of the Modified Fraction 11+111 20 Suspension In order to remove the non-solubilized fraction of the Modified Fraction 11+111 precipitate (i.e., the Modified Fraction 11+111 filter cake), the suspension is filtered, typically using depth filtration. Depth filters that may be employed in the methods provided herein include, metallic, glass, ceramic, organic (such as diatomaceous earth) depth filters, and 25 the like. Example of suitable filters include, without limitation, Cuno 50SA, Cuno 90SA, and Cuno VR06 filters (Cuno). Alternatively, the separation step can be performed by centrifugation rather than filtration. Although the manufacturing process improvements described above minimize IgG losses in the initial steps of the purification process, critical impurities, including PKA activity, 30 amidolytic activity, and fibrinogen content, are much higher when, for example, the 29 11+111 paste is extracted at pH 4.5 or 4.6, as compared to when the extraction occurs at a pH around 4.9 to 5.0 (see, Examples 2 to 5). In order to counter act the impurities extracted in the methods provided herein, it has now been found that the purity of the IgG composition can be greatly enhanced by the 5 addition of a pretreatment step prior to filtration/centrifugation. In one embodiment, this pretreatment step comprises addition of finely divided silica dioxide particles (e.g., fumed silica, Aerosil*) followed by a 40 to 80 minute incubation period during which the suspension is constantly mixed. In certain embodiments, the incubation period will be between about 50 minutes and about 70 minutes, or about 30, 35, 40, 45, 50, 55, 60, 65, 10 70, 75, 80, or more minutes. Generally, the treatment will be performed at between about 0 0 C and about 10 C, or between about 2'C and about 8'C. In certain embodiments, the treatment may be performed at about 0 0 C, 1C, 2'C, 3'C, 4'C, 5 0 C, 6'C, 7'C, 8'C, 9'C, or 10 C. In a particular embodiment, the treatment is performed at between about 2'C and about 10 0 C. 15 The effect of the fumed silica treatment is exemplified by the results found in Example 17. In this example, a Fraction 11+111 precipitate is suspended and split into two samples, one of which is clarified with filter aid only prior to filtration (Figure 7A) and one of which is treated with fumed silica prior to addition of the filter aid and filtration (Figure 7B). As can be seen in the chromatographs and in the quantitated data, the filtrate sample 20 pretreated with fumed silica had a much higher IgG purity than the sample only treated with filter aid (68.8% vs. 55.7%; compare Tables 17 and 18, respectively). In certain embodiments, fumed silica is added at a concentration of between about 20 g/kg 11+111 paste and about 100 g/kg 11+111 paste (i.e., for a Modified Fraction 11+111 precipitate that is extracted at a ration of 1:15, fumed silica should be added at a 25 concentration from about 20 g/16 kg 11+111 suspension to about 100 g/16 kg 11+111 suspension, or at a final concentration of about 0.125% (w/w) to about 0.625% (w/w)). In certain embodiments, the fumed silica may be added at a concentration of about 20 g/kg 11+111 paste, or about 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 g/kg 11+111 paste. In one specific embodiment, fumed silica (e.g., Aerosil 380 or 30 equivalent) is added to the Modified Fraction 11+111 suspension to a final concentration of about 40 g/16 kg 11+111. Mixing takes place at about 2 to 8'C for at least 50 to 70 minutes.

30 In certain embodiments, filter aid, for example Celpure C300 (Celpure) or Hyflo-Supper Cel (World Minerals), will be added after the silica dioxide treatment, to facilitate depth filtration. Filter aid can be added at a final concentration of from about 0.1 kg/kg 11+111 paste to about 0.07 kg/kg 11+111 paste, or from about 0.2 kg/kg 11+111 paste to about 0.06 5 kg/kg 11+111 paste, or from about 0.3 kg/kg 11+111 paste to about 0.05 kg/kg 11+111 paste. In certain embodiments, the filter aid will be added at a final concentration of about 0.1 kg/kg 11+111 paste, or about 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7 kg/kg 11+111 paste. A significant fraction of IgG was being lost during the filtration step of the GAMMAGARD® LIQUID manufacturing process. It was found that the current 10 methods of post-filtration wash, using 1.8 dead volumes of suspension buffer to purge the filter press frames and lines, were insufficient for maximal recovery of IgG at this step. Surprisingly, it was found that at least 3.0 dead volumes, preferably 3.6 dead volumes, of suspension buffer were required in order for efficient recovery of total IgG in the Modified Fraction 11+111 clarified suspension (see, Example 12 and Figure 1). In certain 15 embodiments, the filter press may be washed with any suitable suspension buffer. In a particular embodiment, the wash buffer will comprise, for example, 5 mM monobasic sodium phosphate, 5 mM acetate, and 0.015% glacial acetic acid (v/v). In one aspect, the improvement relates to a method in which a reduced amount of IgG is lost during the Fraction 11+111 suspension filtration step. In one embodiment, the process 20 improvement is realized by post-washing the filter with at least about 3.6 dead volumes of dissolution buffer containing 150 mL glacial acetic acid per 1000 L. As compared to methods previously employed for the clarification of the suspension formed from the second precipitation step (GAMMAGARD* LIQUID), the present invention provides, in several embodiments, methods that result in improved IgG yields 25 and purity in the clarified Fraction 11+111 suspension. In one aspect, the improvement relates to a method in which a reduced amount of IgG is lost in the Modified Fraction 11+111 filter cake. In other aspect, the improvement relates to a method in which a reduced amount of an impurity is found in the clarified Fraction 11+111 suspension. In one embodiment, the process improvements are realized by inclusion of a fumed silica 30 treatment prior to filtration or centrifugal clarification of the Modified Fraction 11+111 suspension. In certain embodiments, the fumed silica treatment will include addition of from about 0.1 kg/kg 11+111 paste to about 0.07 kg/kg 11+111 paste, or from about 0.2 31 kg/kg 11+111 paste to about 0.06 kg/kg 11+111 paste, or from about 0.3 kg/kg 11+111 paste to about 0.05 kg/kg 11+111 paste, or about 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7 kg/kg 11+111 paste, and the mixture will be incubated for between about 50 minutes and about 70 minutes, or about 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or more minutes at a temperature between 5 about 2'C and about 8'C. In another embodiment, the process improvements are realized by inclusion of a fumed silica treatment which reduced the levels of residual fibrinogen, amidolytic activity, and/or prekallikrein activator activity. In another embodiment, the process improvements are realized by washing the depth filter with between about 3 and about 5 volumes of the filter dead volume after 10 completing the Modified Fraction 11+111 suspension filtration step. In certain embodiments, the filter will be washed with between about 3.5 volumes and about 4.5 volumes, or at least about 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0 volumes of the filter dead volume. In a particular embodiment, the filter press will be washed with at least about 3.6 dead 15 volumes of suspension buffer. 6. Detergent Treatment In order to remove additional contaminants from the Modified Fraction 11+111 filtrate, the sample is next subjected to a detergent treatment. Methods for the detergent treatment of plasma derived fractions are well known in the art. Generally, any standard non-ionic 20 detergent treatment may be used in conjunction with the methods provided herein. For example, an exemplary protocol for a detergent treatment is provided below. Briefly, polysorbate-80 is added to the Modified Fraction 11+111 filtrate at a final concentration of about 0.2% (w/v) with stirring and the sample is incubated for at least 30 minutes at a temperature between about 2 to 8'C. Sodium citrate dehydrate is then 25 mixed into the solution at a final concentration of about 8 g/L and the sample is incubated for an additional 30 minutes, with continuous of stirring at a temperature between about 2 to 8'C. In certain embodiments, any suitable non-ionic detergent can be used. Examples of suitable non-ionic detergents include, without limitation, Octylglucoside, Digitonin, 30 Cl2E8, Lubrol, Triton X-100, Nonidet P-40, Tween-20 (i.e., polysorbate-20), Tween-80 32 (i.e., polysorbate-80), an alkyl poly(ethylene oxide), a Brij detergent, an alkylphenol poly(ethylene oxide), a poloxamer, octyl glucoside, decyl maltoside, and the like. In one embodiment, a process improvement is realized by adding the detergent reagents (e.g., polysorbate-80 and sodium citrate dehydrate) by spraying rather than by fluent 5 addition. In other embodiments, the detergent reagents may be added as solids to the Modified Fraction 11+111 filtrate while the sample is being mixed to ensure rapid distribution of the additives. In certain embodiments, it is preferable to add solid reagents by sprinkling the solids over a delocalized surface area of the filtrate such that local overconcentration does not occur, such as in fluent addition. 10 7. Third Precipitation Event - Precipitation G In order to remove several residual small proteins, such as albumin and transferrin, a third precipitation is performed at a concentration of 25% alcohol. Briefly, the pH of the detergent treated 11+111 filtrate is adjusted to between about 6.8 and 7.2, preferably between about 6.9 and about 7.1, most preferably about 7.0 with a suitable pH modifying 15 solution (e.g., 1M sodium hydroxide or IM acetic acid). Cold alcohol is then added to the solution to a final concentration of about 25% (v/v) and the mixture is incubated while stirring to form a third precipitate (i.e., precipitate G). In one aspect, a process improvement relates to a method in which a reduced amount of IgG is lost in the supernatant fraction of the third precipitation step. In certain 20 embodiments, the process improvement is realized by adjusting the pH of the solution to between about 6.8 and about 7.2 immediately after or during the addition of the precipitating alcohol. In another embodiment, the process improvement is realized by maintaining the pH of the solution to between about 6.8 and about 7.2 continuously during the precipitation incubation period. In other embodiments, the pH of the solution 25 is adjusted to between about 6.9 and about 7.1 immediately after or during the addition of the precipitating alcohol, or to a pH of about 6.8, 6.9, 7.0, 7.1, or 7.2 immediately after or during the addition of the precipitating alcohol. In a particular embodiment, the pH of the solution is adjusted to about 7.0 immediately after or during the addition of the precipitating alcohol. In certain embodiments, the pH of the solution is maintained at 30 between about 6.9 to about 7.1 continuously during the precipitation incubation period, or at a pH of about 7.0 continuously during the precipitation incubation period. As such, in certain embodiments, a reduced amount of IgG is lost in the supernatant fraction of the 33 third precipitation step as compared to an analogous precipitation step in which the pH of the solution is adjusted prior to but not after addition of the precipitating alcohol or to an analogous precipitation step in which the pH of the solution is not maintained during the entirety of the precipitation incubation period. In one embodiment, the pH is maintained 5 at the desired pH during the precipitation hold or incubation time by continuously adjusting the pH of the solution. In one embodiment, the alcohol is ethanol. In another embodiment, the process improvement is realized by adding the precipitating alcohol and/or the solution used to adjust the pH by spraying, rather than by fluent addition. As such, in certain embodiments, a reduced amount of IgG is lost in the 10 supernatant fraction of the third precipitation step as compared to an analogous precipitation step in which the alcohol and/or solution used to adjust the pH is introduced by fluent addition. In one embodiment, the alcohol is ethanol. 8. Suspension and Filtration of Precipitate G (PptG) In order to solubilize the IgG content of the precipitate G, a cold extraction buffer is used 15 to re-suspend the PptG. The suspended PptG solution is then filtered with a suitable depth filter having a nominal pore size of between about 0.1 pim and about 0.4 pim. In one embodiment, the nominal pore size of the depth filter is about 0.2 jim (e.g., Cuno VR06 filter or equivalent) to obtain a clarified filtrate. In another embodiment, the suspended PptG solution is centrifuged to recover a clarified supernatant. 20 9. Solvent Detergent Treatment In order to inactivate various viral contaminants which may be present in plasma-derived products, the clarified PptG filtrate is next subjected to a solvent detergent (S/D) treatment. Methods for the detergent treatment of plasma derived fractions are well known in the art (for review see, Pelletier JP et al., Best Pract Res Clin Haematol. 25 2006;19(1):205-42). Generally, any standard S/D treatment may be used in conjunction with the methods provided herein. For example, an exemplary protocol for an S/D treatment is provided below. Briefly, Triton X-100, Tween-20, and tri(n-butyl)phosphate (TNBP) are added to the clarified PptG filtrate at final concentrations of about 1.0%, 0.3%, and 0.3%, 30 respectively. The mixture is then stirred at a temperature between about 18 C and about 25'C for at least about an hour.

34 In one embodiment, a process improvement is realized by adding the S/D reagents (e.g., Triton X-100, Tween-20, and TNBP) by spraying rather than by fluent addition. In other embodiments, the detergent reagents may be added as solids to the clarified PptG filtrate, which is being mixed to ensure rapid distribution of the S/D components. In certain 5 embodiments, it is preferable to add solid reagents by sprinkling the solids over a delocalized surface area of the filtrate such that local overconcentration does not occur, such as in fluent addition. 10. Ion Exchange Chromatography In order to further purify and concentrate IgG from the S/D treated PptG filtrate, cation 10 exchange and/or anion exchange chromatography can be employed. Methods for purifying and concentrating IgG using ion exchange chromatography are well known in the art. For example, U.S. Patent No. 5,886,154 describes a method in which a Fraction 11+111 precipitate is extracted at low pH (between about 3.8 and 4.5), followed by precipitation of IgG using caprylic acid, and finally implementation of two anion 15 exchange chromatography steps. U.S. Patent No. 6,069,236 describes a chromatographic IgG purification scheme that does not rely on alcohol precipitation at all. PCT Publication No. WO 2005/073252 describes an IgG purification method involving the extraction of a Fraction 11+111 precipitate, caprylic acid treatment, PEG treatment, and a single anion exchange chromatography step. U.S. Patent No. 7,186,410 describes an IgG 20 purification method involving the extraction of either a Fraction 1+11+111 or a Fraction II precipitate followed by a single anion exchange step performed at an alkaline pH. U.S. Patent No. 7,553,938 describes a method involving the extraction of either a Fraction 1+11+111 or a Fraction 11+111 precipitate, caprylate treatment, and either one or two anion exchange chromatography steps. U.S. Patent No. 6,093,324 describes a purification 25 method comprising the use of a macroporous anion exchange resin operated at a pH between about 6.0 and about 6.6. U.S. Patent No. 6,835,379 describes a purification method that relies on cation exchange chromatography in the absence of alcohol fractionation. The disclosures of the above publications are hereby incorporated by reference in their entireties for all purposes 30 In one embodiment of the methods of the present invention, the S/D treated PptG filtrate may be subjected to both cation exchange chromatography and anion exchange chromatography. For example, in one embodiment, the S/D treated PptG filtrate is 35 passed through a cation exchange column, which binds the IgG in the solution. The S/D reagents can then be washed away from the absorbed IgG, which is subsequently eluted off of the column with a high pH elution buffer having a pH between about 8.0 and 9.0. In this fashion, the cation exchange chromatography step can be used to remove the S/D 5 reagents from the preparation, concentrate the IgG containing solution, or both. In certain embodiments, the pH elution buffer may have a pH between about 8.2 and about 8.8, or between about 8.4 and about 8.6, or a pH of about 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, or 9.0. In a preferred embodiment, the pH of the elution buffer is about 8.5 ±0.1. 10 In certain embodiments, the eluate from the cation exchange column may be adjusted to a lower pH, for example between about 5.5 and about 6.5, and diluted with an appropriate buffer such that the conductivity of the solution is reduced. In certain embodiments, the pH of the cation exchange eluate may be adjusted to a pH between about 5.7 and about 6.3, or between about 5.9 and about 6.1, or a pH of about 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 15 6.2, 6.3, 6.4, or 6.5. In a preferred embodiment, the pH of the eluate is adjusted to a pH of about 6.0 ± 0.1. The eluate is then loaded onto an anion exchange column, which binds several contaminants found in the preparation. The column flow through, containing the IgG fraction, is collected during column loading and washing. In certain embodiments, the ion exchange chromatographic steps of the present invention can be 20 performed in column mode, batch mode, or in a combination of the two. In certain embodiments, a process improvement is realized by adding the solution used to adjust the pH by spraying, rather than by fluent addition. 11. Nanofiltration and Ultra/Diafiltration In order to further reduce the viral load of the IgG composition provided herein, the anion 25 exchange column effluent may be nanofiltered using a suitable nanofiltration device. In certain embodiments, the nanofiltration device will have a mean pore size of between about 15 nm and about 200 nm. Examples of nanofilters suitable for this use include, without limitation, DVD, DV 50, DV 20 (Pall), Viresolve NFP, Viresolve NFR (Millipore), Planova 15N, 20N, 35N, and 75N (Planova). In a specific embodiment, the 30 nanofilter may have a mean pore size of between about 15 nm and about 72 nm, or between about 19 nm and about 35 nm, or of about 15 rm, 19nm, 35nm, or 72 nm. In a 36 preferred embodiment, the nanofilter will have a mean pore size of about 35 nm, such as an Asahi PLANOVA 35N filter or equivalent thereof. Optionally, ultrafiltration/diafiltration may performed to further concentrate the nanofiltrate. In one embodiment, an open channel membrane is used with a specifically 5 designed post-wash and formulation near the end the production process render the resulting IgG compositions about twice as high in protein concentration (200mg/mL) compared to state of the art IVIGs (e.g., GAMMAGARD* LIQUID) without affecting yield and storage stability. With most of the commercial available ultrafiltration membranes a concentration of 200mg/mL IgG cannot be reached without major protein 10 losses. These membranes will be blocked early and therefore adequate post-wash is difficult to achieve. Therefore open channel membrane configurations have to be used. Even with open channel membranes, a specifically designed post-wash procedure has to be used to obtain the required concentration without significant protein loss (less than 2% loss). Even more surprising is the fact that the higher protein concentration of 15 200mg/mL does not effect the virus inactivation capacity of the low pH storage step. Subsequent to nanofiltration, the filtrate may be further concentrated by ultrafiltration/diafiltration. In one embodiment, the nanofiltrate may be concentrated by ultrafiltration to a protein concentration of between about 2% and about 10% (w/v). In certain embodiments, the ultrafiltration is carried out in a cassette with an open channel 20 screen and the ultrafiltration membrane has a nominal molecular weight cut off (NMWCO) of less than about 100 kDa or less than about 90, 80, 70, 60, 50, 40, 30, or fewer kDa. In a preferred embodiment, the ultrafiltration membrane has a NMWCO of no more than 50 kDa. Upon completion of the ultrafiltration step, the concentrate may further be concentrated 25 via diafiltration against a solution suitable for intravenous or intramuscular administration. In certain embodiments, the diafiltration solution may comprise a stabilizing and/or buffering agent. In a preferred embodiment, the stabilizing and buffering agent is glycine at an appropriate concentration, for example between about 0.20 M and about 0.30M, or between about 0.22M and about 0.28M, or between about 30 0.24M and about 0.26 mM, or at a concentration of about 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0. In a preferred embodiment, the diafiltration buffer contains at or about 0.25 M glycine.

37 Typically, the minimum exchange volume is at least about 3 times the original concentrate volume or at least about 4, 5, 6, 7, 8, 9, or more times the original concentrate volume. The IgG solution may be concentrated to a final protein concentration of between about 5% and about 22% (w/v), or between about 6% and 5 about 18% (w/v), or between about 7% and about 16% (w/v), or between about 8% and about 14% (w/v), or between about 9% and about 12%, or to a final concentration of about 5%, or 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, or higher. Typically, at the end of the concentration process, the pH of the solution will be between about 4.6 to 5.1. 10 [00011 In an exemplary embodiment, the pH of the IgG composition is adjusted to about 4.5 prior to ultrafiltration. The solution is concentrated to a protein concentration of 5 ± 2% w/v through ultrafiltration. The UF membrane has a nominal molecular weight cut off (NMWCO) of 50,000 Daltons or less (Millipore Pellicon Polyether sulfon membrane). The concentrate is diafiltered against ten volumes of 0.25 M glycine 15 solution, pH 4.5 ± 0.2. Throughout the ultra-diafiltration operation the solution is maintained at a temperature of between about 2'C to about 8'C. After diafiltration, the solution is concentrated to a protein concentration of at least 11 % (w/v). 12. Formulation Upon completion of the diafiltration step, the protein concentration of the solution is 20 adjusted to with the diafiltration buffer to a final concentration of between about 5% and about 20% (w/v), or between about 6% and about 18% (w/v), or between about 7% and about 16% (w/v), or between about 8% and about 14% (w/v), or between about 9% and about 12%, or to a final concentration of about 5%, or 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%. In a preferred embodiment, the 25 final protein concentration of the solution is between about 9% and about 11%, more preferably about 10%. The formulated bulk solution is further sterilized by filtering through a membrane filter with an absolute pore size of no more than about 0.22 micron, for example about 0.2 micron. Then the solution is aseptically dispensed into final containers for proper 30 sealing, with samples taken for testing.

38 In one embodiment, the IgG composition is further adjusted to a concentration of about 10.2 ± 0.2% (w/v) with diafiltration buffer. The pH is adjusted to about 4.4 to about 4.9 if necessary. Finally, the solution is sterile filtered and incubated for three weeks at or about 30 0 C. 5 13. Alcohol Addition Advantageously, it has been found that, for purposes of fractionating IgG from plasma, addition of alcohol by spraying rather than fluent addition results in reduced loss of IgG yields. Without being bound by theory, during fluent addition to a plasma fraction, transient local overconcentration of alcohol at the fluid ingress may lead to protein 10 denaturation and irreversible loss and/or precipitation of IgG during steps in which IgG should remain in the supernatant. Furthermore, these effects may by amplified when large volumes of alcohol need to be added, such as in industrial scale purifications involving the fractionation of at least 100 L of pooled plasma. The effect of alcohol addition via spraying is exemplified in Example 14, in which cryo 15 poor plasma samples are precipitated with 8% ethanol introduced by either fluent addition (1 and 2) or spray addition (3 and 4). As can be seen in Table 14, nearly 100% of the IgG present in the cryo-poor plasma is recovered in the supernatant when ethanol is added to the sample by spraying, while 4 to 5% of the IgG is lost upon fluent addition of alcohol. This results in an IgG loss of between about 0.20 and 0.25 g/L at this step 20 alone. In terms of 2007 production levels, this translates into a loss of about 5.3 million grams (5,300 kilograms) of IgG. Given the current market price for IVIG, which ranges from between $50 and $100 per gram, a 4 to 5% loss at this step represents an global economic loss of up to a half billion dollars annually. Accordingly, in one aspect of the methods provided herein, one or more precipitation 25 steps are performed by the spray addition of alcohol. In certain embodiments, spray addition may be performed by using any pressurized device, such as a container (e.g., a spray bottle), that has a spray head or a nozzle and is operated manually or automatically to generate a fine mist from a liquid. In certain embodiments, spray addition is performed while the system is continuously stirred or otherwise mixed to ensure rapid 30 and equal distribution of the liquid within the system.

39 14. Adjustment of pH The protein precipitation profiles of plasma fractions is highly dependent upon the pH of the solution from which the plasma proteins are being precipitated. This fact has been exploited by scientists fractionating plasma proteins since the introduction of the Cohn 5 and Oncley methods in 1946 and 1949, respectively. Traditionally, the pH of a plasma fraction is adjusted prior to alcohol addition to facilitate the highest recovery yields for the component of interest. Advantageously, it has now been found that by adjusting the pH of the solution directly after addition of alcohol or concomitant with alcohol addition results in a more defined and reproducible precipitation. It was found that ethanol 10 addition to plasma fractions results in fluctuations in the pH of the solution, generally by raising the pH of the solution. As such, by adjusting the pH of a plasma fraction to a predetermined pH before but not after alcohol addition, the precipitation reaction will occur at a non-optimal pH. Likewise, precipitation of proteins from a plasma fraction will effect the electrostatic 15 environment and will thus alter the pH of the solution. Accordingly, as a precipitation event is allowed to progress, the pH of the solution will begin to diverge from the predetermined pH value that allows for maximal recovery of the protein species of interest. This is especially true for precipitation events in which a large fraction of the protein is being precipitated, precipitation events in which a high alcohol content is used, 20 and precipitation events that require a long incubation period. The effect of adjusting the pH of a plasma fraction are exemplified by the results found in Example 16. In this example, IgG was precipitated from two samples of a Supernatant I fraction after spray addition of alcohol. The pH of both samples was adjusted to 6.7 before alcohol addition and readjusted to 6.9 after alcohol addition but prior to the 10 25 hour precipitation incubation step. In the first sample (reference), the pH was not adjusted during the 10 hour incubation, while in sample two (continuous adjustment), the pH was constantly adjusted to pH 6.9 during the 10 hour incubation. As can be seen in Table 16, after removal of the modified Fraction 11+111 precipitate from the samples, the first supernatant contained 0.2 g IgG/L plasma, while the second sample, in which the pH 30 was held constant during the precipitation incubation, contained only 0.13 g IgG/L plasma. The reduced loss of 0.07 g IgG/L plasma in the second sample represents, in terms of 2007 production levels, a loss of about 1.9 million grams (1,900 kilograms) of 40 IgG. Given the current market price for IVIG, which ranges from between $50 and $100 per gram, a 1.5% loss at this step represents an global economic loss of up to $200 million dollars annually. Accordingly, in one aspect of the methods provided herein, the pH of a plasma fraction is 5 adjusted directly after the addition of alcohol. In related embodiments, the pH may be adjusted before and after alcohol addition, or during and after alcohol addition, or before, during, and after alcohol addition. In a related embodiment, the pH of a solution is continuously adjusted during one or more alcohol precipitation events or incubations. In certain embodiments, the pH of a solution is continuously adjusted or maintained while 10 the system is continuously stirred or otherwise mixed to ensure rapid and equal distribution of the pH modifying agent within the system. Similar to the case of fluent alcohol addition, it has now been found that the fluent addition of large volumes of a pH modifying agent may cause transient local pH variations, resulting in unwanted protein denaturation or precipitation. Accordingly, in 15 one embodiment of the methods provided herein, pH modifying agents may be introduced into one or more plasma fractionation steps by spray addition. In another embodiment of the methods provided herein, the pH of a plasma fraction or precipitation step may be adjusted by spray addition of a pH modifying agent. In certain embodiments, spray addition may be performed by using any pressurized device, such as 20 a container (e.g., a spray bottle), that has a spray head or a nozzle and is operated manually or automatically to generate a fine mist from a liquid. In certain embodiments, spray addition is performed while the system is continuously stirred or otherwise mixed to ensure rapid and equal distribution of the liquid within the system. III. Concentrated IgG Compositions 25 IVIG compositions comprising whole antibodies have been described for the treatment of certain autoimmune conditions. (See, e.g., U.S. Patent Publication Nos. US 2002/0114802, US 2003/0099635, and US 2002/0098182.) The IVIG compositions disclosed in these references include polyclonal antibodies. 1. Aqueous IgG Compositions 30 In one aspect, the present invention relates to aqueous IgG compositions prepared by the methods provided herein. Generally, the IgG compositions prepared by the novel 41 methods described herein will have high IgG content and purity. For example, IgG compositions provided herein may have a protein concentration of at least about 3% (w/v) and an IgG content of greater than about 90% purity. These high purity IgG compositions are suitable for therapeutic administration, e.g., for IVIG therapy. In one 5 embodiment, the concentration of IgG is about 10% and is used for intravenous administration. In another embodiment, the concentration is about 20% and is used for subcutaneous or intramuscular administration. In one embodiment, the present invention provides an aqueous IgG composition prepared by a method comprising the steps of (a) precipitating a cryo-poor plasmid fraction, in a 10 first precipitation step, with between about 6% and about 10% alcohol at a pH of between about 6.7 and about 7.3 to obtain a supernatant enriched in IgG, (b) precipitating IgG from the supernatant with between about 20% and about 30% alcohol at a pH of between about 6.7 and about 7.3 to form a first precipitate, (c) re-suspending the first precipitate formed in step (b) to form a suspension, (d) treating the suspension formed in 15 step (c) with a detergent, (e) precipitating IgG from the suspension with between about 20% and about 30% alcohol at a pH of between about 6.7 and about 7.3 to form a second precipitate, (f) re-suspending the second precipitate formed in step (e) to form a suspension, (g) treating the suspension formed in step (f) with a solvent and/or detergent, and (h) performing at least one ion exchange chromatography fractionation thereby 20 preparing a composition of concentrated IgG. In a specific embodiment, an IgG composition is provided that is prepared by a method comprising the steps of (a) adjusting the pH of a cryo-poor plasma fraction to about 7.0, (b) adjusting the ethanol concentration of the cryo-poor plasma fraction of step (a) to about 25% (v/v) at a temperature between about -5'C and about -9'C, thereby forming a 25 mixture, (c) separating liquid and precipitate from the mixture of step (b), (d) re suspending the precipitate of step (c) with a buffer containing phosphate and acetate, wherein the pH of the buffer is adjusted with 600 ml of glacial acetic acid per 1000L of buffer, thereby forming a suspension, (e) mixing finely divided silicon dioxide (SiO2) with the suspension from step (d) for at least about 30 minutes, (f) filtering the 30 suspension with a filter press, thereby forming a filtrate, (g) washing the filter press with at least 3 filter press dead volumes of a buffer containing phosphate and acetate, wherein the pH of the buffer is adjusted with 150 ml of glacial acetic acid per 1 OOOL of buffer, thereby forming a wash solution, (h) combining the filtrate of step (f) with the wash 42 solution of step (g), thereby forming a solution, and treating the solution with a detergent, (i) adjusting the pH of the solution of step (h) to about 7.0 and adding ethanol to a final concentration of about 25%, thereby forming a precipitate, (j) separating liquid and precipitate from the mixture of step (i), (k) dissolving the precipitate in an aqueous 5 solution comprising a solvent or detergent and maintaining the solution for at least 60 minutes, (1) passing the solution after step (k) through a cation exchange chromatography column and eluting proteins absorbed on the column in an eluate, (in) passing the eluate from step (1) through an anion exchange chromatography column to generate an effluent, (n) passing the effluent from step (in) through a nanofilter to generate a nanofiltrate, (o) 10 passing the nanofiltrate from step (n) through an ultrafiltration membrane to generate an ultrafiltrate, and (p) diafiltrating the ultrafiltrate from step (o) against a diafiltration buffer to generate a diafiltrate having a protein concentration between about 8% (w/v) and about 12% (w/v), thereby obtaining a composition of concentrated IgG. In certain embodiments, aqueous IgG compositions are prepared using a method 15 provided herein that comprises improvements in two or more of the fractionation process steps described above. For example, in certain embodiments the improvements may be found in the first precipitation step, the Modified Fraction 11+111 precipitation step, the Modified Fraction 11+111 dissolution step, and/or the Modified Fraction 11+111 suspension filtration step. 20 In one embodiment, an aqueous IgG composition is provided that is prepared by a purification method described herein, wherein the method comprises the spray addition of one or more solutions that would otherwise be introduced into a plasma fraction by fluent addition. For example, in certain embodiments the method will comprise the introduction of alcohol (e.g., ethanol) into a plasma fraction by spraying. In other 25 embodiments, solutions that may be added to a plasma fraction by spraying include, without limitation, a pH modifying solution, a solvent solution, a detergent solution, a dilution buffer, a conductivity modifying solution, and the like. In a preferred embodiment, one or more alcohol precipitation steps is performed by the addition of alcohol to a plasma fraction by spraying. In a second preferred embodiment, one or more 30 pH adjustment steps is performed by the addition of a pH modifying solution to a plasma fraction by spraying.

43 In certain embodiments, an aqueous IgG composition is provided that is prepared by a purification method described herein, wherein the method comprises adjusting the pH of a plasma fraction being precipitated after and/or concomitant with the addition of the precipitating agent (e.g., alcohol or polyethelene glycol). In some embodiments, a 5 process improvement is provided in which the pH of a plasma fraction being actively precipitated is maintained throughout the entire precipitation incubation or hold step by continuous monitoring and adjustment of the pH. In preferred embodiments the adjustment of the pH is performed by the spray addition of a pH modifying solution. In one embodiment, the present invention provides aqueous IgG compositions 10 comprising a protein concentration of between about 30 g/L and about 250 g/L. In certain embodiments, the protein concentration of the IgG composition is between about 50 g/L and about 200 g/L, or between about 70 g/L and about 150 g/L, or between about 90 g/L and about 120 g/L, or any suitable concentration within these ranges, for example about 30 g/L, or about 35 g/L, 40 g/L, 45 g/L, 50 g/L, 55 g/L, 60 g/L, 65 g/L, 70 g/L, 75 15 g/L, 80 g/L, 85 g/L, 90 g/L, 95 g/L, 100 g/L, 105 g/L, 110 g/L, 115 g/L, 120 g/L, 125 g/L, 130 g/L, 135 g/L, 140 g/L, 145 g/L, 150 g/L, 155 g/L, 160 g/L, 165 g/L, 170 g/L, 175 g/L, 180 g/L, 185 g/L, 190 g/L, 195 g/L, 200 g/L, 205 g/L, 210 g/L, 215 g/L, 220 g/L, 225 g/L, 230 g/L, 235 g/L, 240 g/L, 245 g/L, 250 g/L, or higher. In a preferred embodiment, the aqueous IgG composition will have a concentration of at or about 10%. 20 In a particularly preferred embodiment, the composition will have a concentration of 10.2 ± 0.2% (w/v) In another preferred embodiment, the aqueous IgG composition will have a concentration of at or about 20%. The methods provided herein allow for the preparation of IgG compositions having very high levels of purity. For example, in one embodiment, at least about 95% of the total 25 protein in a composition provided herein will be IgG. In other embodiments, at least about 96% of the protein is IgG, or at least about 97%, 98%, 99%, 99.5%, or more of the total protein of the composition will be IgG. In a preferred embodiment, at least 97% of the total protein of the composition will be IgG. In another preferred embodiment,, at least 98% of the total protein of the composition will be IgG. In another preferred 30 embodiment,, at least 99% of the total protein of the composition will be IgG. Similarly, the methods provided herein allow for the preparation of IgG compositions which containing extremely low levels of contaminating agents. For example, in certain 44 embodiments, IgG compositions are provided that contain less than about 100 mg/L IgA. In other embodiments, the IgG composition will contain less than about 50 mg/L IgA, preferably less than about 35 mg/L IgA, most preferably less than about 20 mg/L IgA 2. Pharmaceutical Compositions 5 In another aspect, the present invention provides pharmaceutical compositions and formulations comprising purified IgG prepared by the methods provided herein. Generally, the IgG pharmaceutical compositions and formulations prepared by the novel methods described herein will have high IgG content and purity. For example, IgG pharmaceutical compositions and formulations provided herein may have a protein 10 concentration of at least about 7% (w/v) and an IgG content of greater than about 95% purity. These high purity IgG pharmaceutical compositions and formulations are suitable for therapeutic administration, e.g., for IVIG therapy. In a preferred embodiment, a pharmaceutical IgG composition is formulated for intravenous administration (e.g., IVIG therapy). 15 In one embodiment, the pharmaceutical compositions provided herein are prepared by formulating an aqueous IgG composition isolated using a method provided herein. Generally, the formulated composition will have been subjected to at least one, preferably at least two, most preferably at least three, viral inactivation or removal steps. Non-limiting examples of viral inactivation or removal steps that may be employed with 20 the methods provided herein include, solvent detergent treatment (Horowitz et al., Blood Coagul Fibrinolysis 1994 (5 Suppl 3):S21-S28 and Kreil et al., Transfusion 2003 (43):1023-1028, both of which are herein expressly incorporated by reference in their entirety for all purposes), nanofiltration (Hamamoto et al., Vox Sang 1989 (56)230-236 and Yuasa et al., JGen Virol. 1991 (72 (pt 8)):2021-2024, both of which are herein 25 expressly incorporated by reference in their entirety for all purposes), and low pH incubation at high temperatures (Kempf et al., Transfusion 1991 (31)423-427 and Louie et al., Biologicals 1994 (22):13-19). In certain embodiments, pharmaceutical formulations are provided having an IgG content of between about 80 g/L IgG and about 120 g/L IgG. Generally, these IVIG formulations 30 are prepared by isolating an IgG composition from plasma using a method described herein, concentrating the composition, and formulating the concentrated composition in a solution suitable for intravenous administration. The IgG compositions may be 45 concentrated using any suitable method known to one of skill in the art. In one embodiment, the composition is concentrated by ultrafiltration/diafiltration. In some embodiments, the ultrafiltration device used to concentrate the composition will employ an ultrafiltration membrane having a nominal molecular weight cut off (NMWCO) of 5 less than about 100 kDa or less than about 90, 80, 70, 60, 50, 40, 30, or fewer kDa. In a preferred embodiment, the ultrafiltration membrane has a NMWCO of no more than 50 kDa. Buffer exchange may be achieved using any suitable technique known to one of skill in the art. In a specific embodiment, buffer exchange is achieved by diafiltration. In one specific embodiment, a pharmaceutical composition of IgG is provided, wherein 10 the IgG composition was purified from plasma using a method comprising the steps of (a) precipitating a cryo-poor plasmid fraction, in a first precipitation step, with between about 6% and about 10% alcohol at a pH of between about 6.7 and about 7.3 to obtain a supernatant enriched in IgG, (b) precipitating IgG from the supernatant with between about 20% and about 30% alcohol at a pH of between about 6.7 and about 7.3 to form a 15 first precipitate, (c) re-suspending the first precipitate formed in step (b) to form a suspension, (d) treating the suspension formed in step (c) with a detergent, (e) precipitating IgG from the suspension with between about 20% and about 30% alcohol at a pH of between about 6.7 and about 7.3 to form a second precipitate, (f) re-suspending the second precipitate formed in step (e) to form a suspension, (g) treating the suspension 20 formed in step (f) with a solvent and/or detergent, (h) performing at least one ion exchange chromatography fractionation; (i) performing a solvent detergent treatment; and (j) subjecting the composition to nanofiltration, thereby preparing a composition of IgG. In a specific embodiment, a pharmaceutical composition of IgG is provided, wherein the 25 IgG composition was purified from plasma using a method comprising the steps of (a) adjusting the pH of a cryo-poor plasma fraction to about 7.0, (b) adjusting the ethanol concentration of the cryo-poor plasma fraction of step (a) to about 25% (v/v) at a temperature between about -5'C and about -9'C, thereby forming a mixture, (c) separating liquid and precipitate from the mixture of step (b), (d) re-suspending the 30 precipitate of step (c) with a buffer containing phosphate and acetate, wherein the pH of the buffer is adjusted with 600 ml of glacial acetic acid per 1 OOOL of buffer, thereby forming a suspension, (e) mixing finely divided silicon dioxide (SiO2) with the suspension from step (d) for at least about 30 minutes, (f) filtering the suspension with a 46 filter press, thereby forming a filtrate, (g) washing the filter press with at least 3 filter press dead volumes of a buffer containing phosphate and acetate, wherein the pH of the buffer is adjusted with 150 ml of glacial acetic acid per 1000L of buffer, thereby forming a wash solution, (h) combining the filtrate of step (f) with the wash solution of step (g), 5 thereby forming a solution, and treating the solution with a detergent, (i) adjusting the pH of the solution of step (h) to about 7.0 and adding ethanol to a final concentration of about 25%, thereby forming a precipitate, (j) separating liquid and precipitate from the mixture of step (i), (k) dissolving the precipitate in an aqueous solution comprising a solvent or detergent and maintaining the solution for at least 60 minutes, (1) passing the 10 solution after step (k) through a cation exchange chromatography column and eluting proteins absorbed on the column in an eluate, (in) passing the eluate from step (1) through an anion exchange chromatography column to generate an effluent, (n) passing the effluent from step (in) through a nanofilter to generate a nanofiltrate, (o) passing the nanofiltrate from step (n) through an ultrafiltration membrane to generate an ultrafiltrate, 15 and (p) diafiltrating the ultrafiltrate from step (o) against a diafiltration buffer to generate a diafiltrate having a protein concentration between about 8% (w/v) and about 12% (w/v), thereby obtaining a composition of concentrated IgG. In certain embodiments, a pharmaceutical composition of IgG is provided, wherein the IgG composition is prepared using a method provided herein that comprises 20 improvements in two or more of the fractionation process steps described above. For example, in certain embodiments the improvements may be found in the first precipitation step, the Modified Fraction 11+111 precipitation step, the Modified Fraction 11+111 dissolution step, and/or the Modified Fraction 11+111 suspension filtration step. In certain embodiments, a pharmaceutical composition of IgG is provided, wherein the 25 IgG composition is prepared using a purification method described herein, wherein the method comprises the spray addition of one or more solutions that would otherwise be introduced into a plasma fraction by fluent addition. For example, in certain embodiments the method will comprise the introduction of alcohol (e.g., ethanol) into a plasma fraction by spraying. In other embodiments, solutions that may be added to a 30 plasma fraction by spraying include, without limitation, a pH modifying solution, a solvent solution, a detergent solution, a dilution buffer, a conductivity modifying solution, and the like. In a preferred embodiment, one or more alcohol precipitation steps is performed by the addition of alcohol to a plasma fraction by spraying. In a second 47 preferred embodiment, one or more pH adjustment steps is performed by the addition of a pH modifying solution to a plasma fraction by spraying. In certain embodiments, a pharmaceutical composition of IgG is provided, wherein the IgG composition is prepared by a purification method described herein, wherein the 5 method comprises adjusting the pH of a plasma fraction being precipitated after and/or concomitant with the addition of the precipitating agent (e.g., alcohol or polyethelene glycol). In some embodiments, a process improvement is provided in which the pH of a plasma fraction being actively precipitated is maintained throughout the entire precipitation incubation or hold step by continuous monitoring and adjustment of the pH. 10 In preferred embodiments the adjustment of the pH is performed by the spray addition of a pH modifying solution. In one embodiment, the present invention provides a pharmaceutical composition of IgG comprising a protein concentration of between about 70 g/L and about 130 g/L. In certain embodiments, the protein concentration of the IgG composition is between about 15 80 g/L and about 120 g/L, preferably between about 90 g/L and about 110 g/L, most preferably of about 100 g/L, or any suitable concentration within these ranges, for example about 70 g/L, 75 g/L, 80 g/L, 85 g/L, 90 g/L, 95 g/L, 100 g/L, 105 g/L, 110 g/L, 115 g/L, 120 g/L, 125 g/L, or 130 g/L. In a preferred embodiment, a pharmaceutical composition is provided having a protein concentration of at or about 100 g/L. In a 20 particularly preferred embodiment, the pharmaceutical composition will have a protein concentration of at or about 102 g/L. In another embodiment, the present invention provides a pharmaceutical composition of IgG comprising a protein concentration of between about 170 g/L and about 230 g/L. In certain embodiments, the protein concentration of the IgG composition is between about 25 180 g/L and about 220 g/L, preferably between about 190 g/L and about 210 g/L, most preferably of about 200 g/L, or any suitable concentration within these ranges, for example about 170 g/L, 175 g/L, 180 g/L, 185 g/L, 190 g/L, 195 g/L, 200 g/L, 205 g/L, 210 g/L, 215 g/L, 220 g/L, 225 g/L, or 230 g/L. In a preferred embodiment, a pharmaceutical composition is provided having a protein concentration of at or about 200 30 g/L. The methods provided herein allow for the preparation of IgG pharmaceutical compositions having very high levels of purity. For example, in one embodiment, at 48 least about 95% of the total protein in a composition provided herein will be IgG. In other embodiments, at least about 96% of the protein is IgG, or at least about 97%, 98%, 99%, 99.5%, or more of the total protein of the composition will be IgG. In a preferred embodiment, at least 97% of the total protein of the composition will be IgG. In another 5 preferred embodiment,, at least 98% of the total protein of the composition will be IgG. In another preferred embodiment,, at least 99% of the total protein of the composition will be IgG. Similarly, the methods provided herein allow for the preparation of IgG pharmaceutical compositions which containing extremely low levels of contaminating agents. For 10 example, in certain embodiments, IgG compositions are provided that contain less than about 100 mg/L IgA. In other embodiments, the IgG composition will contain less than about 50 mg/L IgA, preferably less than about 35 mg/L IgA, most preferably less than about 20 mg/L IgA. The pharmaceutical compositions provided herein will typically comprise one or more 15 buffering agents or pH stabilizing agents suitable for intravenous, subcutaneous, and/or intramuscular administration. Non-limiting examples of buffering agents suitable for formulating an IgG composition provided herein include glycine, citrate, phosphate, acetate, glutamate, tartrate, benzoate, lactate, histidine or other amino acids, gluconate, malate, succinate, formate, propionate, carbonate, or any combination thereof adjusted to 20 an appropriate pH. Generally, the buffering agent will be sufficient to maintain a suitable pH in the formulation for an extended period of time. In a preferred embodiment, the buffering agent is glycine. In some embodiments, the concentration of buffering agent in the formulation will be between about 100 mM and about 400 mM, preferably between about 150 mM and about 25 350 mM, more preferably between about 200 mM and about 300 mM, most preferably about 250 mM. In a particularly preferred embodiment, the IVIG composition will comprise between about 200 mM and about 300 mM glycine, most preferably about 250 mM glycine. In certain embodiments, the pH of the formulation will be between about 4.1 and about 30 5.6, preferably between about 4.4 and about 5.3, most preferably between about 4.6 and about 5.1. In particular embodiments, the pH of the formulation may be about 4.1, 4.2, 49 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, or 5.6. In a preferred embodiment, the pH of the formulation will be between about 4.6 and about 5.1. In some embodiments, the pharmaceutical compositions provided herein may optionally further comprise an agent for adjusting the osmolarity of the composition. Non-limiting 5 examples of osmolarity agents include mannitol, sorbitol, glycerol, sucrose, glucose, dextrose, levulose, fructose, lactose, polyethylene glycols, phosphates, sodium chloride, potassium chloride, calcium chloride, calcium gluconoglucoheptonate, dimethyl sulfone, and the like. Typically, the formulations provided herein will have osmolarities that are comparable to 10 physiologic osmolarity, about 285 to 295 mOsmol/kg (Lacy et al., Drug Information Handbook - Lexi-Comp 1999:1254. In certain embodiments, the osmolarity of the formulation will be between about 200 mOsmol/kg and about 350 mOsmol/kg, preferably between about 240 and about 300 mOsmol/kg. In particular embodiments, the osmolarity of the formulation will be about 200 mOsmol/kg, or 210 mOsmol/kg, 220 15 mOsmol/kg, 230 mOsmol/kg, 240 mOsmol/kg, 245 mOsmol/kg, 250 mOsmol/kg, 255 mOsmol/kg, 260 mOsmol/kg, 265 mOsmol/kg, 270 mOsmol/kg, 275 mOsmol/kg, 280 mOsmol/kg, 285 mOsmol/kg, 290 mOsmol/kg, 295 mOsmol/kg, 300 mOsmol/kg, 310 mOsmol/kg, 320 mOsmol/kg, 330 mOsmol/kg, 340 mOsmol/kg, 340 mOsmol/kg, or 350 mOsmol/kg. 20 The IgG formulations provided herein are generally stable in liquid form for an extended period of time. In certain embodiments, the formulations are stable for at least about 3 months at room temperature, or at least about 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 months at room temperature. The formulation will also generally be stable 6or at least about 18 months under refrigerated conditions (typically 25 between about 2'C and about 8'C), or for at least about 21, 24, 27, 30, 33, 36, 39, 42, or 45 months under refrigerated conditions. IV. Methods of Treatment As routinely practiced in the modem medicine, sterilized preparations of concentrated immunoglobulins (especially IgGs) are used for treating medical conditions that fall into 30 these three main classes: immune deficiencies, inflammatory and autoimmune diseases, and acute infections. These IgG preparations may also be useful for treating multiple 50 sclerosis (especially relapsing-remitting multiple sclerosis or RRMS), Alzheimer's disease, and Parkinson's disease. The purified IgG preparation of this invention is suitable for these purposes, as well as other clinically accepted uses of IgG preparations. The FDA has approved the use of IVIG to treat various indications, including allogeneic 5 bone marrow transplant, chronic lymphocytic leukemia, idiopathic thrombocytopenic purpura (ITP), pediatric HIV, primary immunodeficiencies, Kawasaki disease, chronic inflammatory demyelinating polyneuropathy (CIDP), and kidney transplant with a high antibody recipient or with an ABO incompatible donor. In certain embodiments, the IVIG compositions provided herein are useful for the treatment or management of these 10 diseases and conditions. Furthermore, off-label uses for IVIG are commonly provided to patients for the treatment or management of various indications, for example, chronic fatigue syndrome, clostridium difficile colitis, dermatomyositis and polymyositis, Graves' ophthalmopathy, Guillain-Barre syndrome, muscular dystrophy, inclusion body myositis, Lambert-Eaton 15 syndrome, Lupus erythematosus, multifocal motor neuropathy, multiple sclerosis (MS), myasthenia gravis, neonatal alloimmune thrombocytopenia, Parvovirus B19 infection, pemphigus, post-transfusion purpura, renal transplant rejection, spontaneous Abortion/Miscarriage, stiff person syndrome, opsoclonus Myoclonus, severe sepsis and septic shock in critically ill adults, toxic epidermal necrolysis, chronic lymphocytic 20 leukemia, multiple myeloma, X-linked agammaglobulinemia, and hypogammaglobulinemia. In certain embodiments, the IVIG compositions provided herein are useful for the treatment or management of these diseases and conditions. Finally, experimental use of IVIG for the treatment or management of diseases including primary immune deficiency, RRMS, Alzheimer's disease, and Parkinson's disease has 25 been proposed (U.S. Patent Application Publication No. U.S. 2009/0148463, which is herein incorporated by reference in its entirety for all purposes). In certain embodiments, the IVIG compositions provided herein are useful for the treatment or management of primary immune deficiency, RRMS, Alzheimer's disease, or Parkinson's disease. In certain embodiments comprising daily administration, an effective amount to be 30 administered to the subject can be determined by a physician with consideration of individual differences in age, weight, disease severity, route of administration (e.g., intravenous v. subcutaneous) and response to the therapy. In certain embodiments, an 51 immunoglobulin preparation of this invention can be administered to a subject at about 5 mg/kilogram to about 2000 mg/kilogram each day. In additional embodiments, the immunoglobulin preparation can be administered in amounts of at least about 10 mg/kilogram, at last 15 mg/kilogram, at least 20 mg/kilogram, at least 25 mg/kilogram, at 5 least 30 mg/kilogram, or at least 50 mg/kilogram. In additional embodiments, the immunoglobulin preparation can be administered to a subject at doses up to about 100 mg/kilogram, to about 150 mg/kilogram, to about 200 mg/kilogram, to about 250 mg/kilogram, to about 300 mg/kilogram, to about 400 mg/kilogram each day. In other embodiments, the doses of the immunoglobulin preparation can be greater or less. 10 Further, the immunoglobulin preparations can be administered in one or more doses per day. Clinicians familiar with the diseases treated by IgG preparations can determine the appropriate dose for a patient according to criteria known in the art. In accordance with the present invention, the time needed to complete a course of the treatment can be determined by a physician and may range from as short as one day to 15 more than a month. In certain embodiments, a course of treatment can be from 1 to 6 months. An effective amount of an IVIG preparation is administered to the subject by intravenous means. The term "effective amount" refers to an amount of an IVIG preparation that results in an improvement or remediation of disease or condition in the subject. An 20 effective amount to be administered to the subject can be determined by a physician with consideration of individual differences in age, weight, the disease or condition being treated, disease severity and response to the therapy. In certain embodiments, an IVIG preparation can be administered to a subject at dose of about 5 mg/kilogram to about 2000 mg/kilogram per administration. In certain embodiments, the dose may be at least 25 about 5 mg/kg, or at least about 10 mg/kg, or at least about 20 mg/kg, 30 mg/kg, 40 mg/kg, 50 mg/kg, 60 mg/kg, 70 mg/kg, 80 mg/kg, 90 mg/kg, 100 mg/kg, 125 mg/kg, 150 mg/kg, 175 mg/kg, 200 mg/kg, 250 mg/kg, 300 mg/kg, 350 mg/kg, 400 mg/kg, 450 mg/kg, 500 mg/kg, 550 mg/kg, 600 mg/kg, 650 mg/kg, 700 mg/kg, 750 mg/kg, 800 mg/kg, 850 mg/kg, 900 mg/kg, 950 mg/kg, 1000 mg/kg, 1100 mg/kg, 1200 mg/kg, 1300 30 mg/kg, 1400 mg/kg, 1500 mg/kg, 1600 mg/kg, 1700 mg/kg, 1800 mg/kg,, 1900 mg/kg,, or at least about 2000 mg/kg.

52 The dosage and frequency of IVIG treatment will depend upon, among other factors. the disease or condition being treated and the severity of the disease or condition in the patient. Generally, for primary immune dysfunction a dose of between about 100 mg/kg and about 400 mg/kg body weight will be administered about every 3 to 4 weeks. For 5 neurological and autoimmune diseases, up to 2 g/kg body weight is implemented for three to six months over a five day course once a month. This is generally supplemented with maintenance therapy comprising the administration of between about 100 mg/kg and about 400 mg/kg body weight about once every 3 to 4 weeks. Generally, a patient will receive a dose or treatment about once every 14 to 35days, or about every 21 to 28 10 days. The frequency of treatment will depend upon, among other factors. the disease or condition being treated and the severity of the disease or condition in the patient. In a preferred embodiment, a method of treating an immunodeficiency, autoimmune disease, or acute infection in a human in need thereof is provided, the method comprising administering a pharmaceutical IVIG composition of the present invention. In a related 15 embodiment, the present invention provides IVIG compositions manufactured according to a method provided herein for the treatment of an immunodeficiency, autoimmune disease, or acute infection in a human in need thereof. In certain embodiments, the immunodeficiency, autoimmune disease, or acute infection is selected from allogeneic bone marrow transplant, chronic lymphocytic leukemia, 20 idiopathic thrombocytopenic purpura (ITP), pediatric HIV, primary immunodeficiencies, Kawasaki disease, chronic inflammatory demyelinating polyneuropathy (CIDP), kidney transplant with a high antibody recipient or with an ABO incompatible donor, chronic fatigue syndrome, clostridium difficile colitis, dermatomyositis and polymyositis, Graves' ophthalmopathy, Guillain-Barr6 syndrome, muscular dystrophy, inclusion body myositis, 25 Lambert-Eaton syndrome, Lupus erythematosus, multifocal motor neuropathy, multiple sclerosis (MS), myasthenia gravis, neonatal alloimmune thrombocytopenia, Parvovirus B19 infection, pemphigus, post-transfusion purpura, renal transplant rejection, spontaneous Abortion/Miscarriage, stiff person syndrome, opsoclonus Myoclonus, severe sepsis and septic shock in critically ill adults, toxic epidermal necrolysis, chronic 30 lymphocytic leukemia, multiple myeloma, X-linked agammaglobulinemia, hypogammaglobulinemia, primary immune deficiency, RRMS, Alzheimer's disease, and Parkinson's disease.

53 Examples The following examples are provided by way of illustration only and not by way of limitation. Those of skill in the art will readily recognize a variety of non-critical parameters that could be changed or modified to yield essentially the same or similar 5 results. Example 1 The present example demonstrates that significant amounts of fibrinogen, amidolytic activity, prekallikrein activity, and lipoproteins can be removed from an extracted modified Fraction 11+111 paste suspension by treatment with Aerosil prior to filtration. 10 Fumed silica (Aerosil 380) is currently used to adsorb fibrinogen, amidolytic activity, prekallikrein activity, and lipoproteins. To investigate the effect of Aerosil in more detail, six modified Fraction 11+111 suspensions were treated with varying amounts of Aerosil prior to filtration Briefly, dissolution buffer containing 5mM sodium acetate / 5mM sodium dihydrogen phosphate buffer pH 4.5 was used to re-suspend modified 15 11+111 paste, prepared as described herein, at a ratio of 15 grams dissolution buffer per gram 11+11I paste. After paste addition, the suspension was stirred for one hour at between 2'C and 8'C in a pH controlled environment (pH IPC limits: 4.9 to 5.3). We have found that the pH of this suspension normally shifts to a pH of about 5.1, and thus further pH adjustment is not necessary. After an additional extraction, for at least 120 20 minutes, Aerosil 380, at between 0 and 100 mg per gram 11+111 paste, was added to the containers and the suspensions were incubated for one hour. Diatomaceous earth was added prior to depth filtration with a Cuno 50SA filter. After filtration, the filters were washed with extraction buffer containing 8 g L 1 citrate and 0.2% polysorbate 80 (pH 5.0) and the wash was added to the filtrate. The combined filtrate and wash solution was then 25 treated with Polysorbate 80 to further solubilize hydrophobic impurities, for example lipoproteins, and the IgG was precipitated with 25% ethanol (pH 7) at between -8'C and -10 C. The resulting Ppt G precipitate was almost white and possessed higher IgG purity. The precipitate was then dissolved in purified water at a ratio of 7 grams water per 2 grams Ppt G precipitate. 30 The IgG solutions were analyzed for IgG recovery and impurities following the Cuno filtration step. Specifically, levels of amidolytic activity (PL-1), PKA activity, and fibrinogen were measured (Table 3). Notably, as seen in Table 3, extraction protocols 54 using 40 to 60mg Aerosil 380 per g 11+111 paste resulted in acceptable levels of IgG recovery with significant decreases in amidolytic and PKA activity, as well as a significant decrease in the level of fibrinogen in the filtrate. Compared to extractions performed without Aerosil treatment, the addition of 40mg Aerosil 380 per gram 11+111 5 paste resulted in an almost 90% reduction of PKA activity and fibrinogen content and a 60% reduction of amidolytic activity, while maintaining similar IgG recovery (73%). Table 1. Effect of the amount of Aerosil 380 at the 11+111 Cuno Filtration step (Extraction with GAMMAGARD* LIQUID Conditions) Aerosil IgG IgG PL-1 PKA Fibrinogen mg g- g L- pmol min' g U ga mg g- protein Reovr protein fptG ll+111 paste plasma Recovery protein (Ppt G) (Ppt G) _____G) 0 4.9 72% 1.3 2403 19.5 20 5.2 82 % 0.7 974 8.2 40 4.8 73% 0.5 290 2.1 60 4-8 71% 0.3 90 0.1 below detection 80 4.2 63 % limit 37 0.0 below detection 10 100 4.3 65 % limit 16 0.0 Example 2 The present example demonstrates that significant amounts of fibrinogen can be removed from an extracted modified Fraction II+III paste suspension by treatment with Aerosil 15 prior to filtration. One purpose of the present experiment was to find suitable conditions for efficient fibrinogen removal without incurring significant losses of IgG. Modified 11+111 paste, prepared according to the method provided herein, was dissolved in 5mM sodium acetate / 5mM monobasic sodium phosphate buffer pH 4.5. The dissolution ratio was 15kg of buffer perl kg 11+111 paste. The amount of acetic acid 20 added to the buffer was chosen in a way that pH after sixty minutes stirring was 4.9. In order to fully homogenize the suspension, it was stirred up to twenty hours at 2 to 8 0 C before being separated into 6 portions of 50 ml each in 1 00ml beakers, where varying amounts of Aerosil 380 were already present, as given in Table 2. The 11+111 suspension solutions were then stirred for 80 minutes in the presence of the Aerosil, prior to 55 processing and analysis. After stirring all samples were centrifuged with a Heraeus Cryofuge 8500i at 4600 RPM for 30minutes at 4'C in 50ml falcon tubes. In this experiment, IgG measurements were taken using the nephelometric test, which was chosen due to the more accurate values, compared to the ELISA test, at the high 5 concentrations found in 11+111 suspension solutions. To minimize the irritation of unspecific turbidity, the samples were filtered through 0.45ptm filters prior to testing. For IgM, IgA, and fibrinogen, ELISA tests were preferred due to the lower concentrations of these impurities in the suspension. The results of the experiment are shown below in Table 2. 10 To further characterize the effect of Aerosil treatment on fibrinogen removal and IgG loss as described in Example 1, Aerosil concentrations were further titrated between 0 mg and 40 mg per gram modified 11+111 paste. The results shown in Table 2 confirm the high capacity of Aerosil to reduce fibrinogen in this fraction. Notably, use of 40mg per gram 11+111 paste results in almost 90% reduction of fibrinogen, while only reducing IgG 15 recovery in the filter cake by 10%. Table 2. Results from the variation of dissolution conditions after extraction of 11+111 with 5mM 20 NaAc / 5mM NaH 2

PO

4 pH 4.5 at a dissolution ratio of 1kg 11+111 plus 15kg of buffer after centrifugation Values in supernatant Dissolution conditions Protein (Bi ret) IgM ELISA IgG neph. 1A ELISA Fibrinogen ELISA E ! E 3~ E -5 E Blank 80min 80 50 15 1376 0-69 8-4 0.29 71 4.44 0.61 4 0.25 Aerosil 5 000 8 1 34U U 0/ 1 311 .28 / 30 4.51k 8 0.61 3 3 0.22 Aerosil 10 n g 0 j i 1 067 8i4 0.291 697 4.3C 1 0.621 72 0.17 Ae te 80 5.0 1 15 12.0 610 7 4451 0.281 7 4.3 00 0.62 230 0.14 - v0 5 56 7 7 6 0.291 677 4. 4 0.58 5 0.06 Aroi4080 1 12.21 061 7 44 0.28f6.1 4.141 89 0.56 41 0.03 Example 3 56 The present example demonstrates suitable conditions that allow for highly efficient extraction of IgG from a modified Fraction 11+111 paste, while limiting the levels of detrimental impurities. Specifically, parameters including the concentration of acetic acid used in the 11+111 dissolution buffer and aerosil treatment of the extracted solution 5 prior to filtration were examined. II+III paste was extracted in 5mM sodium acetate, 5mM sodium dihydrogen phosphate and variable amounts of concentrated acetic acid, as shown in Table 1, for 180 minutes at between 2'C and 8'C, followed by addition of Aerosil 380 as shown in Table 1. After one hour of stirring, the suspension was clarified by Cuno 50SA filtration in the presence 10 of diatomaceous earth. Post-wash of the filter was carried out with the same buffer as for the extraction except the different amount of acetic acid, as given in Table 1, using 40% of the volume of the suspension prior to filtration. Precipitate G precipitation in the presence of 25% ethyl alcohol; 8g L-' sodium citrate, and 0.2% Tween 80 (pH 7) at -8'C was performed and after 8 hours hold time, separation was performed by centrifugation 15 with Heraeus Cryofuge 8500i in stainless steel beakers at 4600 RPM for 30 minutes at 1 0 0 C. The precipitate was dissolved in a 1:2 ratio in purified water. Table 3. The influence of the acetic acid amount of pH adjustment of extraction buffer and Aerosil amount for clarification on IgG yield and purity in Ppt G and IgG loss in the filter cake 20 57 Aerosil (mg g-1 1141) 0 20 40 40 dissolution buffer acetic acid (g L-) 0.40 0.40 0.40 0.51 pH 4.52 4.52 4.52 4.46 1i+111 extract pH 5.00 5.00 5.00 4.94 conductivity (nS cm 1 ) 1.340 1.340 1.340 .344 pre/post-wash acetic acid (g L-) 0.12 0.12 0.12 0.12 buffer pH 5.02 52 5.02 5.02 CAE albumin (%) 11.9 12.5 12.3 10.7 CAE a/p-globulin 25.5 22.9 19 17.2 filtrate 11+111 CAE denatured protein 3.2 0.0 0.0 0.0 CAE (% y-globulin) 59.4 64.6 68.8 72.1 pH 5.00 5.03 5.04 4.92 IgG loss filter cake (g L1 plasma) 0.09 0.20 0.56 .2 CAE albumin (%) 0.3 0.5 0.3 0.3 CAE a/p-globulin 16.2 14.3 12.5 13.0 CAE denatured protein 0.0 0.0 0.0 0.0 PptG dissolved CAE (% y-globulin) 83.5 7.2 86.7 fibrinogen (mg L1 plasma) 129 32 <4 4 PKA (IU mg 1 protein) 126 60 9 10 PL-1 (pmol ml) g-1) 0.9 0.6 0.5 0.6 PptG supernatant pH 7.20 7.35 7.30 6.96 supernet ntsPptG (g L 1 plasma) 0.14 0.13 0.11 0.09 As can be seen in Table 1, Aerosil addition to the 11+11I paste suspension has a marked influence on y-globulin purity in the Ppt G fraction. Without Aerosil the y-globulin purity is only 83.5%, while addition of 40mg Aerosil per gram 11+111 paste to the 11+111 5 paste suspension increases the y-globulin purity to 87.2%. As evidenced, Aerosil treatment leads to a significant reduction of fibrinogen, PKA and amidolytic activity. One drawback of the impurity adsorption on Aerosil is that IgG loss in the filter cake is increased with increasing amounts of Aerosil. However, as shown in Table 1, higher concentrations of acetic acid in the extraction buffer partially counterbalances the effect 10 of Aerosil on IgG loss in the filter cake, and further reduced IgG loss in the supernatant Ppt G fraction. As can be seen in Table 1, increasing the amount of acetic acid in the dissolution buffer from 400 pL per L paste to 510 pL per L paste, reduced the amount of IgG lost in the filter cake by almost 50%. Advantageously, the higher acetic acid concentration does not affect the y-globulin purity in the Ppt G fraction (87.2% pure 15 using 400 pL per L paste vs. 86.7% pure using 510 pL per L paste). Furthermore, the results show that the difference in pH value caused by the different amount of acetic acid is negligible, due to the high buffer capacity of acetic acid near its pka value of 4.75 (Merck). This suggests that for better accuracy in large-scale manufacturing, acetic acid should be added by weight. Thus, the influence of Aerosil on purity is much higher than 58 the influence of acetic acid on purity, in the investigated range, as shown with the y globulin content measured by CAE. Example 4 The results found in Example 3 suggested that the amount of IgG lost in the filter cake is 5 strongly dependent on the amount of acetic acid used for pH adjustment of the extraction buffer at a given Aerosil concentration. In order to further characterize this effect, modified 11+111 paste was extracted in purified water for about 120 minutes to obtain a homogeneous suspension and divided into 4 parts. These parts were adjusted to pH 3.8, 4.2, 4.6, and 5.0, respectively, with 1M acetic acid followed by a second extraction time 10 for another 120 minutes. Afterwards, Aerosil treatment was done with 40 mg Aerosil 380 per gram 11+111 paste. After one hour stirring the suspension was clarified by Cuno 50SA filtration in the presence of diatomaceous earth. Post-wash of the filter was carried out with 100 percent of the volume of the suspension prior filtration with extraction buffer adjusted to the pH as given above. The filtrate was treated with 8g L-1 sodium 15 citrate and 0.2% Tween 80, adjusted to pH 7.0, and IgG was precipitated with 25% alcohol at -8'C. PptG precipitate was recovered by centrifugation at 4600 RPM for 30 minutes at -10 0 C in a Heraeus Cryofuge 8500i using stainless steel beakers. The precipitate was then dissolved in purified water at a ratio of 7 grams water per 2 grams Ppt G precipitate. The relevant fractions were then assayed for IgG recovery, PKA 20 activity, fibrinogen content, and amidolytic activity, to determine the pH dependence of recovery (Table 4). Table 4. pH dependent removal of fibrinogen, PKA and amidolytic activity by extraction and clarification with Aerosil treatment 59 Precipitate G pH concentration IgG loss in extraction of acetic acid igG loss in PptG and after pH filter cake supernatant IgG loss I fibrinogen PL-1 clarification adjustment (g L (g L: 1 (g LC PKA (mg L_' (pmol mL acetic acid (mM) plasma) plasma) plasma) (IU mg) plasma) 9L 3.8 75 0.02 0.85 0.87 138 243 4.2 25 0.04 0.53 0.57 35 182 4.6 10 0.07 0.05 0.12 2 99 2 5.0 5 0.19 0.06 0.25 0.6 3 0.5 3.8 75 - - - 116 304 3.8 4.2 25 0.02 0.34 0.36 44 313 2.6 4.6 10 0.04 0.52 0.56 8 148 1.7 5.0 5 0.14 0.09 0.23 3 10 <0.2 Table 4 shows that PKA, amidolytic activity (PL-1), and fibrinogen removal with Aerosil is less effective at lower pH during clarification. It can be seen from the results obtained here, that the most effective pH for effective removal of PKA, amidolytic activity (PL-1), 5 and fibrinogen, while maintaining efficient IgG recovery in the Ppt G fraction, is about pH 5. High concentrations of acetic acid lead to a significant IgG loss in Ppt G supernatant (0.85g L- in the presence of 75mM acetic acid) while IgG loss in the filter cake is minimized. Example 5 10 To determine the dependence of Aerosil treatment on the results found in Example 4, the experiment was repeated, but with the Aerosil treatment step omitted. Briefly, 11+111 paste was extracted in purified water for about 120 minutes to obtain a homogeneous suspension and divided into 4 parts. These parts were adjusted to pH 3.8, 4.2, 4.6, and 5.0, respectively, with IM acetic acid followed by a second extraction time for another 15 120 minutes. Afterwards, the suspension was clarified by Cuno 50SA filtration in the presence of diatomaceous earth. Post-wash of the filter was carried out with 100 percent of the volume of the suspension prior filtration with extraction buffer adjusted to the pH as given above. The filtrate was treated with 8g L- sodium citrate and 0.2% Tween 80, adjusted to pH 7.0, and IgG was precipitated with 25% alcohol at -8'C. Ppt G precipitate 20 was recovered by centrifugation at 4600 RPM for 30 minutes at -10 C in a Heraeus Cryofuge 8500i using stainless steel beakers. The precipitate was then dissolved in purified water at a ratio of 7 grams water per 2 grams Ppt G precipitate. The relevant fractions were then assayed for IgG recovery, PKA activity, fibrinogen content, and amidolytic activity, to determine the pH dependence of recovery (Table 5).

60 Table 5. pH dependent removal of fibrinogen, PKA and amidolytic activity by extraction and clarification without Aerosil treatment Precipitate G pH concentration IgG loss in extraction of acetic acid IgG loss in PptG and after pH filter cake supernatant IgG loss I fibrinogen PL-1 clarification adjustment (g L- 1 (g L- (g L1 PKA (mg L1 (pmol mL 4 acetic acid (mM) plasma) plasma) plasma) (IU mg-) plasma) g-) 3.8 75 0.00 0.42 0.42 214 173 3.9 4.2 25 0.01 0.19 0.20 170 134 3.2 4.6 10 0.01 0.09 0.10 38 193 1.4 5.0 5 0.09 0.04 0.13 6.4 114 0.4 3.8 75 0.00 0.53 0.53 193 355 3.8 4.2 25 0.00 0.28 0.28 171 346 3.2 4.6 10 0.01 0.14 0.15 131 340 1.5 5.0 5 0.16 0.05 0.21 5.3 189 <0.2 5 Consistent with the results found in Example 4, increasing the pH of the extraction/dissolution buffer to 5.0 resulted in a small increase in the IgG lost in the filter cake, however, this loss was more than offset by a larger decrease in the loss of IgG in the Ppt G supernatant. When the results of Example 4 and Example 5 are compared, it can be seen that Aerosil 10 treatment reduces the amount of residual PKA activity found in the dissolved PptG fraction when the 11+111 paste is extracted at lower pHs (3.8, 4.2, and 4.6), but not at pH 5.0 (Figure 2). Conversely, Aerosil treatment significantly reduces the fibrinogen content of the dissolved Ppt G fraction when the 11+111 paste is extracted at higher pHs (Figure 3; compare pH 4.6 and 5.0 to pH 3.8 and 4.2). Aerosil treatment does not appear 15 to affect the level of residual amidolytic activity found in the dissolved Ppt G fraction (Figure 4). Notably, the level of all three contaminants in the dissolved Ppt G fraction is considerably reduced when the 11+111 paste is extracted at pH 5.0, as compared to pH 3.8, 4.2, and 4.6. 20 Example 6 As can be seen in the Examples above, IgG losses in the filter cake and Ppt G supernatants are minimized when the 11+111 paste is extracted at a pH of around 4.5 to 4.6. However, it is also evidenced in the previous examples, that critical impurities, 61 including PKA activity, amidolytic activity, and fibrinogen content, are much higher when the 11+111 paste is extracted at pH 4.5 or 4.6 compared to when the extraction occurs at a pH around 4.9 to 5.0. Accordingly, the present example was performed to determine if the higher impurity levels seen when the 11+11I paste is extracted at pH 4.5 5 could be offset by increasing the amount of Aerosil used to adsorb contaminants, while maintaining low levels of IgG loss in the filter cake and Ppt G supernatant. Along these lines, extraction of modified 11+111 paste was performed as before, with extraction buffer having a pH of 4.5. Increasing amounts of Aerosil 380, up to 200 mg per g 11+111 paste, were then added and the suspension was stirred for one hour. Further 10 processing of the sample was performed as above. As can be seen in Table 6, both fibrinogen and PKA activity removal is significantly improved by clarification with high amounts of Aerosil. IgG losses in the filter cake due to binding onto Aerosil is increased with high amounts of Aerosil, although this effect was somewhat offset by a decrease in the loss of IgG in the Ppt G supernatant. 15 Significantly, however, amidolytic activity could not be reduced by high amounts of Aerosil when the 11+11I paste is extracted at pH 4.5. Furthermore, although y-globulin purity is improved with higher amounts of Aerosil, in all cases it is still below the specification limit of >86% for Ppt G. likely because of the low pH at the extraction and clarification. 20 Table 6. Table 6 gives the results of the variation in Aerosil concentration with extraction and clarification of pH 4.5 Precipitate G IgG loss in amount of IgG loss in PptG Aerosil in filter cake supernatant IgG loss 7 fibrinogen PL-1 CAE (% mg per (g L' (g L- (g L' PKA (mg L-1 (pmol mL gamma gram 11+111 plasma) plasma) plasma) (IU mg1) plasma) g) globulin) 0 0.01 0.21 0,22 177.1 272 5.4 69.1 40 0.13 0.50 0.63 9.3 173 1.8 76.8 100 0.11 0.30 0.41 0.1 76 6.1 79.4 below det. 200 0.25 0.08 0.33 Limit 10 4.5 84.1 Example 7 62 The present example demonstrates the effect of the extraction buffer pH on the removal of impurities following II+III paste re-suspension and clarification. Low pH extraction of modified 11+111 paste was performed at pH 4.2 using a ratio of 15 grams buffer per gram 11+111 paste. The suspension was then split into 3 parts and the pH 5 adjusted to 4.5, 4.7, or 5.0 respectively with 3M Tris. Afterwards, each solution was further split into two parts, which were incubated for one hour at either 4'C or 25'C. Filtration with Cuno 50(90)SA was performed using a 10 mM sodium acetate post-wash buffer having the same pH as the respective clarification buffer. The filtrates were treated with 8g L-1 citrate and 0.2% Tween 80, and then IgG was precipitated by addition 10 of 25% ethyl alcohol at -10 0 C for at least 8 hours. The precipitate was recovered by centrifugation as described previously, and the precipitate was dissolved into a 2-fold volume of purified water. The resulting suspension was filtered using a Cuno VR06 filtration devise, in a final solution having a conductivity of about 1.3mS cm-1. To evaluate the various conditions, the level of IgG, IgA, IgM, transferrin, fibrinogen, 15 and other impurities were determined. The results of this analysis are given in Table 7, which shows the pH dependency of clarification of 11+111 paste suspension. Within the pH range of 4.5 to 5.0 IgA, IgM, transferring, and fibrinogen amount does not vary in a wide range, but other unwanted proteins are present at a higher levels when the lower pH buffers are used. It was calculated that these other impurities comprise 10% of the total 20 protein at pH 4.5, but less than 1% at pH 5. The IgG content is the highest at pH 5.0, while the temperature dependence of IgG content and impurity levels, between 4'C and 25'C, is negligible. Table 7. 25 Table 7 compares the reduction of impurities from 11+111 dissolved to VR06 filtrate by variation in pH and temperature during 1 hour incubation after re-suspension of 11+111 paste and subsequent filtration after low pH extraction without additives 63 oH cf of Pro- ___ ~neub3,on -empera~ure adc oct, of mIctbatoi igG calculated fdtratic, and first nephelo IgA igM transferrin ibriogen :her steps fil-rafon s-eo step metrc EUSA ELISA ELISA ELISA impurities 11+11 dissolved 55.0 79 3-6 1.3 3.0 29.3 4C Cuno 90-filtrate 51.7 8-5 4.0 1.6 2.5 31.7 Ppt G dissolved 64.4 8.3 4.4 0.1 2.8 20.0 4- VRO6-filtrate 71.8 9.5 5.1 0.1 3.0 10.6 1+1! dissolved 55.0 7.9 3.6 1.3 3.0 29.3 CuIo 90-f4ltrate 52.3 8-0 4.2 1.6 2.6 31.3 Ppt G dissolved 64.5 7.4 4.8 0.1 3.8 19.4 VR064iltrate 72.5 9.1 5.0 0.1 3.3 9.9 11+d! dissolved 55.0 7.9 3.6 1.3 3.0 29.3 4C CuRo 50-filtrate 49.4 8.2 3.7 1.6 2.5 34.6 Ppt G dissolved 68.8 9.5 5.0 0.1 3.5 13.2 4.7 VR06-fitrate 765 9.8 5.4 0.1 3.5 4.7 11+1h dissolve ed 55.0 7.9 3.6 1.3 3.0 29.3 C Cuno 50-filtrate 49.6 8.6 37 1.5 3.1 33.6 2 5: Ppt G dissolved 66.9 8 4.9 0.1 4.1 15.2 VRO6-filtrate 75.8 10.2 5.3 0.1 4.3 4.3 11+111 dissolved 55.0 7.9 3.6 1.3 3.0 29.3 4*C Cuno 50-fitrate 52.5 9.3 3.4 1.7 2.1 31.0 Ppt G dissolved 76.9 10-1 4.9 0.1 3.0 5.0 5.0 _VRO641trate 83.6 10.6 4.5 0.1 3.0 0.0 .11+11H dissolved 55.0 7.9 3.6 1.3 3.0 29.3 25*C Curno 50-filtrate 53.4 8.9 3.4 1.8 2.6 30.0 Ppt G dissolved 76.6 10.3 4.8 0.1 3.9 4.3 C R6-fi6ltrate 79.9 10.9 4.7 0.1 3.6 0.8 As can be seen in Table 8, further analysis of the dissolved Ppt G fraction and VR06 filtrate indicate that use of buffers having a pH of 4.5 for the 11+111 clarification and 11+111 filtrate treatment steps, results in increased level of aggregates and low molecular weight 5 components. This effect is further enhanced when the steps are performed at 25'C, rather than 4'C. Conversely, when the samples are treated at higher pH (pH 5.0), the resulting Ppt G suspensions and filtrate contain higher levels of -350 kDa material (dimeric IgG or IgA) than do the solutions treated at pH 4.5 (Table 8). Furthermore, the lower pH treatments resulted in higher amidolytic activity levels than did treatment at pH 10 5.0. Table 8. Influence of pH and temperature during incubation and filtration of 11+111 paste suspension on PKA and amidolytic activities of Precipitate G dissolved and on the molecular size distribution in VR06 filtrate.

64 pH d Ppt G dissolved VRD-ftrate mcub-Aion tempe-aure an I c t C f icubation f ltrat eO and ir st PKA adivily amdd yD adtiviy (PL- ) moeculia size disi (% steps fil:ra in sIC-p >450 ~350 60 < pH temp. *C IU mL I g' nmot mLm'i~ nmot mn~1W.gi kBa kDa kDa kDa F5 4 60.2 2028 171 8 5788 28.33 6.61 63.21 1.85 4.5 25 103.4 3569 239A 8264 29.44 6.02 61.76 2.79 4 1343.2 38029 152.1 4306 23.71 8.82 65.82 1.64 4. 25 2215.9 67702 180.2 5506 24.54 8.02 6506 2.38 .0 4 134.5 4009 67.6 2015 17.81 10.78 7003 138 5 0 25 186.6 5738 87.3 2685 19. 16 10.54 68.84 1 46 Example 8 The results presented in Tables 7 and 8 show that the re-suspension of 11+111 precipitate should be performed at refrigerated temperatures (2'C to 8'C) and that pH should be kept 5 at pH 5.0 in order to minimize dissolution of high (>450KDa) and low (>70KDa) molecular weight components, as well as components having amidolytic activity. Effective clarification after 11+111 paste suspension will reduce the impurity load for chromatography downstream processing of Ppt G and is therefore key for meeting the IVIG final container specifications reproducibly. To further validate this finding, 10 modified 11+111 paste was dissolved and processed, as above, in buffers having a pH of 4.5, 4.7, or 5.0. As seen in Table 9, IgM is removed more efficiently by a pH of 5.0 during 11+111 paste suspension and clarification than removal at pH 4.5. In this experiment IgG yield is similar at pH 5.0 and 4.5. Table 9 15 IgG, IgA, IgM, transferrin and fibrinogen yield at various steps of 11+111 paste re suspension, filtration and Ppt G precipitation 65 pH - of incation temperature and ot of ioubation f iration and firstt ttal IgG nep. igA I'gM transfenin fb r.gen steps filtration step step protein ELSA EUSA ESA ELISA EISA 11+111 dissolved 100.0 10.0 100.0 100.0 10010 100 Cuno 50 fItrate 100.2 92.9 100.2 97.8 1187 86.3 Guno 90 filtrate 97.0 911 105.3 108. 123.2 80.1 Ppt C supernatarit 33.5 4.4 - - Ppt G dissolved 71.7 83.9 75.6 89.6 5.0 665 4.5 \/RQ6 filtrate 65.3 85.2 78.8 93.1 5.2 64.8 11+111 dissolved 100.0 100.0 1 l00. 1 10.0 100.0 Cuno 50fil rate 101 92.3 100.9 104.4 113.2 96.7 25*C Guno 90 fltrate 97.2 92.4 98.9 113.4 123.9 ew6 Ppt Gsupernatant 33.8 5.1 - Ppt G dissolved 72.9 85.5 68.8 97.5 4.7 89.9 VRO6 filtrate 68.3 90.0 78.9 95.9 5.5 75.0 II+Illdisso ved 10 0 100.0 100.D 100.0 100. 100 Cuno 50 filtrate 93.5 83.9 98.0 98.0 115.9 75.3 4"C Ppt G supernatant 27.5 2.7 - - Ppt G dissolved 64.8 81.1 78.2 90.2 4.5 73-9 4.7 \R06 filtrate 60.5 84.1 75.0 92.1 5.1 70.2 11+111 dissol ed 100. 100.0 1 100 100.0 0 100. 100.0 Curno 50 fItrate 94.7 85.3 103.1 98. 113.8 95.8 25*C Ppt G supernatant 28. 4.1 - - - Ppt G dissolved 65.3 79.5 73.1 90.9 5.0 87.0 VRO6 filtrate 61.9 85.3 80.7 93.0 5.3 86.9 11+11! dissol ed 100.0 100.0 100.0 100.0 100.0 100.0 Cuio 50 tltrate 86.1 82.3 101.5 81.5 117.5 59.8 4*C Ppt G supernatant 26.0 4.1 - - - Ppt G dissolve ed 58.1 81.2 74.8 79.3 4-5 57-0 5.0 VRO6 filtrate 54.0 82.1 72.5 67.8 4.7 52.5 11+111 dissolved 100.0 10o0 100.0 100.0 100.0 100.0 Cunio 50 f rate 88.0 85.4 99.7 83.2 124.1 754 25*C Ppt G supernatant 23.4 1. - Pp G dissolved 60.5 84.2 79.0 81.6 4.5 78.2 VRO6 filtrate 59.0 85.7 82.0 77.6 4.5 69.0 Example 9 To evaluate the pH optimum at the 11+111 paste extraction step, for minimized proteolytic activities in the filtrate, pH during extraction and filtration was varied in a wider range 5 from pH 3.8 to 7.8. For this purpose modified 11+111 paste was extracted at low pH in a ratio of 1+8. After a short time of stirring, to obtain a homogeneous dispersion, the suspension was divided into 8 parts, the pH adjusted with acetic acid or Tris buffer to either pH 3.8, 4.2, 4.6, 5.0, 6.6, 7.0, 7.4 or 7.8, and extracted for an additional 120 minutes. Afterwards, pH was adjusted to 5.1 and clarification was done by 10 centrifugation in 50mL Falcon tubes. Ppt G precipitation was performed under standard 66 conditions. Amidolytic activity and PKA was measured in the Ppt G dissolved fraction as indicated in Figures 5 and 6. As can be seen in the sample stored at 4'C in Figure 5, amidolytic activity is minimized when the 11+111 paste is extracted at pH 5.0. Further emphasizing the point that the 5 samples should not be kept at elevated (room temperature) for extended periods of time, amidolytic activity was elevated after storage of the Ppt G dissolved fraction at room temperature for one week. Similarly, as seen in Figure 6, PKA activity is minimized when the 11+111 paste is extracted at pH 5.0 or higher. Example 10 10 The present example evaluates the pH dependency on IgG yield loss during extraction and clarification. Briefly, 110 grams of modified II+III paste was re-suspended at ratio of 15 grams purified water per gram 11+111 paste, followed by extraction for 120 minute. The sample was then divided into four parts and the pH adjusted with acetic acid to pH 3.8, 4.2, 4.6, or 5.0. Samples were then clarified by Cuno 50SA filtration at the same pH 15 used for each extraction and Ppt G precipitation. The results of two such experiments are summarized below in Tables 10 and 11. Table 10. Protein and IgG recoveries in the filtrates as well as the MSD and CAE results of the re dissolved Precipitate G's 3811 41 pH extraction and 3 8 4.2 4.6 5.0 18 4.2 4-6 5,0 cianfication concentration of etic acid 77 ad justment retete 100.3 99.6 92.8 76.0 106.4 107.5 99.7 81A0 filtrate 'W F IgGre ey >450ka 19.2 20.6 14.8 132 22.5 22.8 20.7 167 MSD (% ~350kDa 8.7 7.6 10.5 11.7 5.2 5.0 7-7 9,4 Prec1tate area ~-160kDa 69.5 69.2 72.9 74.2 66.0 65.6 67.5 72,A S <70ka 2.7 2.7 1.8 1.0 6.2 5.6 41 1,9 20 CAE (% gamma globulin) 67,4 68.3 78.1 86.7 68.3 69.8 77.5 85.1 67 Table 11 IgG loss during extraction and clarification as well as proteolytic activities and fibrinogen in the re-dissolved Precipitate G ___________ ~Precipitate G _____ p H concentraton IgG loss in extraction of acetic acid igG loss in PptG and after pH filter cake supernatant igG loss I fibrinogen PL-1 clarification adjustment (g L g L (g L' PKA (mg L ( (ipol mL acetic acid (mM) pasrna) plasma) plasma) (IU mg ) plasma) 3.8 75 0.00 042 0.42 214 173 3.9 4.2 25 0.01 0.19 0.20 170 134 3.2 4.6 10 0 01 0.09 0.10 38 193 1.4 5.0 5 0.09 0.04 0.13 6.4 114 0.4 3.8 75 0.00 0.53 0.53 193 355 3.8 4.2 25 0.00 028 0.28 171 346 3.2 4.6 10 0:01 0.14 0.15 131 340 1.5 5.0 5 0.05 0.21 5.3 189 0.2 5 The data above confirms the results shown in Figures 5 and 6 concerning the activation of proteolytic enzymes by low pH extraction. Taken together, the data demonstrate that low pH extraction causes less IgG loss due to the increased solubility of all proteins. These results are consistent with the examples provided above. Additionally, the IgG losses shown in Table 11 suggest that higher concentrations of acetic acid, resulting in 10 lower pH, results in less IgG loss in the filter cake but higher IgG loss in Precipitate G supernatant. This phenomenon might be explained by the higher acetate concentrations at the precipitation step after low pH extraction. Example 11 To determine suitable 11+111 extraction conditions, a protocol employing low pH 15 extraction with purified water adjusted with acetic acid to pH 4.3 and readjustment to pH 4.9 before filtration was compared with extraction in 5mM sodium acetate / 5 mM sodium di-hydrogen phosphate with 600g acetic acid per 1000 liter of extraction buffer, resulting in a dissolution pH of 4.8 to 4.9. The experiments were performed in pilot scale, starting with 3.8 to 5kg of modified 11+111 paste. All experiments included Aerosil 20 treatment with 4 0g Aerosil per kg 11+111 paste. For clarification, a Strassburger filter press with filter frames of 30cm*30cm equipped with Cuno 50SA filter sheets was used. Post wash was performed with 4 dead volumes of the filter press, with a 5mM sodium acetate / 5mM sodium di-hydrogen phosphate buffer with 150gram acetic acid per 1000 liter of buffer. Centrifugation of precipitate G was performed with a Cepa* Z61H 68 centrifuge at 17000 RPM (rotor diameter of 10.5cm) at a flow rate of 40 liter per hour. The results of the experiment, done in triplicate, is shown in Table 12. Table 12 Comparison of low pH extraction at pH 4.3 and shift of pH to 4.9 prior to Aerosil 5 treatment with extraction by improved GAMMAGARDg LIQUID conditions with 600 g glacial acetic acid per 1000 L of extraction buffer p ie E a nit PO0&DENG2 PD:909NG2 P21509NG2 PD220NG2 P02509N G2 PD20 NG2 method _ow pH-e nation G00g C1 Ac per 1000L e xra nbufer 11 i-paste vLot# VNEGJ039 VN GBJO2 VNGBJ 16J VNGBJ216 VGJC22 VN EGJ-39 k - 5,00 5,00 4;97 4,96 4,96 3,86 PEQ L 106.65 118.70 123,32 123,31 11765 8235 l~nextrac protein 0 13 6 t310 1364 1336 1347 1022 protein y e d (BIURET' .L 12.3 110 1 1 106 115 12.4 a vid (ESA L 6,09 569 615 550 606 6,38 igA yield (ELISA) g L06 0,96 0,93 1.00 101 1,10 lgM yield ELISA L 14: 0.10 0.47 0,40 0A3 04 prten ____ 57 107 03 955 92633 protein y BIRTi ___ L 9,0 8.5 8,4 7,7 11,5 12.4 G yieId (EUSA> g L 5,7 5,2 5.45 ,02 6.06 6.38 YiA ield (ELISA L 103 068 0.96 0,9D 1 01 1.10 M vie d ELISA L 32 0.39 0.37 0.27 C43 048 I~ ~ ~ ~ ~~~C IG dElA 0 ,7 Ppt G- upematant ___ _____ _____ _____ _____ protin 0 196 130 f 188 187 168 10 protein yEd d 1 (BIURET ZLS 1.1 1. IgG yield EUSA) L L .05 0,02 0.03 0.05 0,03 O.c As seen in Table 12, both extraction protocols result in similar IgG recoveries. Given the results of Examples 3 through 10, which show that various impurities can be minimized 10 by extraction of 11+111 paste at pH 5.0, the results provided in Table 12 show that extraction at pH 4.8 to 4.9 with 600g glacial acetic acid per 1000 L of extraction buffer is superior to extraction at low pH and subsequent adjustment to pH 4.8 to 5.0. Example 12 During manufacturing, filter press frames and lines connecting to and from the tanks 15 have a significant void volume, which is still filled with suspension or filtrate before 69 post-wash is started. When the post wash is finished this void volume remains in the filter press. Standard protocols account for this void volume by washing with between one and two dead volumes of the filter press. In order to determine if standard post-filter washes allow for efficient recovery of total IgG, experiments using varying volumes of 5 wash buffer were performed on large-scale manufacturing IgG purifications. Figure 1 shows the dependency of post-wash volumes (as measured by dead or void volumes) on the levels of residual IgG and total protein. Notably, as seen in Figure 1, a post-filtration wash using about 2-fold filter press dead volume results in significant loss of IgG recovery, as the wash solution contains about 10 1.5 gram IgG per L wash solution. Surprisingly, it was found that 3.6-fold filter press dead volume of post-wash buffer is required for efficient recovery of IgG (denoted by arrow in Figure 1). Further post-washing beyond 3.6 dead volumes of the filter press is not expedient, as it will lead to dilution of the filtrate without additional IgG recovery. Example 13 15 During the II+III precipitation step, alcohol concentration was increased from 20 to 25% and the temperature was lowered from -5'C to -7'C. When dissolving the 11+111 paste, at least 600 mL glacial acetic acid was used per 1000L volume to adjust pH of 11+111 paste re-suspension buffer, in contrast to previously use ratio of 510 mL glacial acetic acid / 1000 L buffer. The extraction ratio was 1 + 15 with the acetic acid buffer. For 20 clarification, 0.04 to 0.06 gram of Aerosil (typically at the low end of this range, e.g., 0.04 g) was added for each gram of 11+111 paste. For post-wash, about four (4 x) filter press dead volumes of post-wash buffer was used. For example, 4.3 x filter press dead volumes was used in one particular experiment whereas 3.6 x volumes was used in another experiment. The four times or more dead volumes post-wash was increased from 25 previously used 1.8 x dead volumes. The buffer was adjusted with 150 mL glacial acetic acid was used per 1000 L buffer, an increase from previously 120 mL glacial acetic acid / 1000 L buffer. These changes led to an 8% higher yield of IgG and a purity of at least 86% y-globulin. Very low residual amount of IgG was found in the filter cake extract, when extracted with 0.1 M sodium phosphate + 150 mM NaCl (pH 7.4, conductivity 25.5 30 mS/cm). Example 14 70 A. Optimization of fractionation I: ethanol addition by spraying versus fluent-wise addition; pH adjustment to pH 7.0 or 7.5 after ethanol addition Table 13 shows IgG yield by the manufacturing methods currently in use and provides a comparison reference in the experiments described below. 15-20% of IgG is lost from 5 Cohn pool to filtrate. About 0.4 g IgG per liter plasma is lost in the 11+111 supernatant. Table 13 IgG Yield (2009) g/L plasma % of Cohn pool Fraction LA BI Vienna LA B5 L.A. Vienna L.A. (source) (source) (Rec.) (source) (source) (Rec.) Cohn pool 6.18 6.26 7.49 * 100 100 100 (5.28- (5.43- (6.41 7.02) 6.68) 8.41) 11+111 0.41 0.39 0.37 6.6 6.2 4.9 Supernatant (0.23- (0.33- (0.23 0.63) 0.47) 0.48) 11+111 5.77 5.87 7.12 93.4 93.8 95.1 precipitate (calculated) 11+111 4.93 5.19 6.43 80 83 86 filtrate ( .1 flrt (4.21- (4.11- (6.11 5.57) 5.48) 7.02) * LA B5 recovered plasma Cohn pool: lower IgG concentration due to saline chase. Average LA B1 recovered plasma Cohn pool: 8.52 g/L. 10 71 Method Cohn pool was thawed at 24-27'C for 6-7 hours in a 14-liter bucket. Afterwards the material was mixed overnight at 2-8'C. The pool was then divided into four parts (800 g each): 5 1: Fluent-wise ethanol addition, followed by pH adjustment to 7.0 2: Fluent-wise ethanol addition, followed by pH adjustment to 7.5 3. Ethanol addition by spraying, followed by pH adjustment to 7.0 4. Ethanol addition by spraying, followed by pH adjustment to 7.5 All parts were first cooled to 0 0 C. 8% ethanol was then added to parts 1 and 2 fluent 10 wise and by spraying to parts 3 and 4 using a spray head. In both methods ethanol was added at approximately the same speed. During ethanol addition, the cryostat was adjusted to -5OC and 75 ml ethanol was added to each part while mixing. The pH was adjusted to either 7.0 or 7.5 by 1M acetic acid. The solution was then incubated for 1 hour. After the incubation the solution was centrifuged with a beaker centrifuge (4600 15 rpm; 30 min; -2'C). Results IgG yields were measured nephelometrically and are shown in Table 14. Almost 100% IgG yield in the fractionation I supernatant was obtained with the improved method (ethanol spraying) while with conventional ethanol addition 0.2 to 0.25 g/L plasma was 20 lost. These results indicate that the improved method may lead to an increase of IgG yield of up to 0.2 g/L plasma in manufacturing. Table 14 IgG neph (mean of 3) Sample Weight mg/mi g % Purity (%) g/L (g) Plasma Cryo-poor 800 5.72 4.57 100.00 12.2 5.72 Plasma Supernatant 1 856 5.10 4.37 95.57 12.6 5.46 72 Supernatant 2 853 5.16 4.41 96.36 12.7 5.51 Supernatant 3 853 5.36 4.58 100.14 13.1 5.72 Supernatant 4 848 5.33 4.52 98.90 13.0 5.65 B. Pilot Scale: Fractionation I (spray v. fluent-wise; pH adjustment to 7.4 after ethanol addition) and Fractionation 11+111 (pH adjustment to 6.7 before ethanol addition, readjustment to 6.9 after ethanol addition) 5 Example 15 Method 2.8 kg plasma was thawed while mixing at 2'C. Fraction I: 8% ethanol was added and the pH was adjusted to 7.4 using 5 M acetic acid. While mixing, the suspension was cooled to a temperature of -2'C. Spraying conditions were obtained using a spray head. 10 In both methods ethanol and 5 M acetic acid addition was performed at approximately the same speed. After 1 hour incubation, the solution was centrifuged using a CEPA centrifuge at a temperature of -4'C. Fraction 11+111: pH was adjusted to 6.7 using a pH 4 buffer, then 25% ethanol was added (1) by spraying or (2) by fluent-wise as conventionally performed. The pH was 15 then readjusted to 6.9. Incubation was conducted for 10 hours at -7'C. Results IgG loss during fraction 11+111 at 25% ethanol was measure nephelometrically and is shown in Table 15. The IgG measurements had a certain variation, the average value of the optimized method were therefore taken. 20 Table 15 IgG Loss Fraction I Fraction 11+111 IgG in the filtrate supernatant, 25% ethanol added Experiment g per liter plasma g per liter plasma % of Cohn pool 73 NG2C73 0.47 0.08 85.28 NG2C73-1 0.34 0.03 92.27 NG2C73-2 0.05 0.06 95.94 Average 0.29 0.06 91.16 Reference (ethanol 0.29 0.10 87.38 addition Fluent wise) Up to the point of fraction II+III precipitate only 0.35 g IgG / L plasma was lost. A yield increase of 0.04 g IgG per liter plasma during fractionation 11+111 using spraying method was achieved, compared to 25% ethanol addition fluent-wise; and a yield increase of 0.3 5 g IgG per liter plasma was achieved (averaged from the range of 0.4 to 0.06 g/L), compared to 20% ethanol addition fluent-wise as currently used in manufacturing. The IgG yield in the filtrate is significantly higher compared to the reference and far above the 80 to 86% achieved currently in manufacturing with addition of 20% ethanol fluent wise at II+III precipitation. 10 C. Fractionation 11+111 (20% ethanol): maintain initial pH all over fractionation 11+111 Example 16 Method 50 liter plasma was thawed while mixing at 17-20'C for 27 hours. Fractionation I was performed as mentioned in the above sections as the optimized process. Supernatant I 15 was separated into two parts: (1) worst case pH adjustment: pH adjustment before and after ethanol addition but not during incubation period. (2) optimized pH adjustment: pH adjustment before and after ethanol addition and further readjustment of the pH during hold time. The solution was constantly stirred during hold 20 time.

74 pH of the supernatant of I was adjusted in both parts to 6.7 before ethanol addition using pH 4 buffer. Ethanol was added by spraying and pH was readjusted to 6.9 after ethanol addition. In part (1) the pH adjustment was carried out with less care to simulate a worst case 5 scenario. pH of the solution was adjusted directly after ethanol addition but not during the incubation. In part (2) the pH was readjusted to a constant value of 6.8 to 7.0 during incubation time of 10 hours. Results IgG was again measure nephelometrically and is shown in Table 16. By constant 10 readjustment of the pH to a constant value of about 6.9 during the hold time, only 0.13 g IgG per liter plasma was lost compared to an average of 0.4 g/L plasma in large-scale manufacturing. Yield increase of 0.07 g IgG per liter plasma was achieved in comparison to reference (without spraying but with constant stirring during hold period). Yield increase of about 0.25 g IgG per liter plasma was achieved compared to the 15 conventional method currently in use (loss of 0.38 g IgG per liter plasma, see Table 13). Table 16 Volume IgG measured nephelometrically Sample kg Yield (%) g/L plasma Pool Plasma 45.20 100.00 4.90 Fraction I Supernatant I 68.66 102.61 5.03 Optimized pH Supernatant 11+111 53.09 0.26 0.13 adjustment Reference Supernatant 11+111 52.69 0.41 0.20 Conclusion IgG loss in 11+111 supernatant is reduced from the current level of 0.4 g IgG / L plasma in 20 manufacturing batches to a level of 0.13 g/L plasma at precipitation with 20% ethanol, and to a level of less than 0.08 g/L plasma at precipitation with 25% ethanol when 75 ethanol is added by spraying and a continuous pH of 6.9 ± 0.1 is maintained during precipitation. At precipitation I, ethanol addition before pH adjustment by spraying leads to an IgG yield increase of 0.1 to 0.2 g/L plasma in fractionation I supernatant. 5 Discussion IgG was measured nephelometrically in all experiments and can have a variance of at least -/+ 5.0% (as indicated by the manufacturer of the nephelometer, Siemens AG). It is therefore possible that the actual yield increase obtained by the improved method during manufacturing may be slightly lower or higher than indicated in the examples. 10 As additional proof of the yield increase by the new and improved method, the precipitate IgG weight was compared to the average precipitate IgG weight obtained from the same plasma source in manufacturing. 18 kg precipitate IgG is obtained per 1000 liter US source Cohn Pool by the method currently used in manufacturing, in contrast to the pilot scale study (section B above) where 20.8 kg precipitate IgG was 15 obtained (20% ethanol and optimized pH adjustment at fractionation 11+111, all buffer and ethanol addition by spraying). This is an increase of more than 2 kg precipitate IgG per 1000 liter Cohn Pool. Example 17 This example demonstrates that the addition of a fumed silica treatment step prior to 20 filtration of the Fraction 11+111 suspension results in higher purity IgG filtrates. Briefly, cryo-poor plasma was fractionated as described above to the Fraction 11+111 stage, at which point it was split into two samples. The first sample was clarified only by addition of filter aid prior to standard Fraction 11+111 suspension filtration (Figure 7A). the second sample was subjected to fumed silica pretreatment, as described herein, prior to addition 25 of filter aid and standard Fraction 11+111 suspension filtration (Figure 7B). The protein components of the filtrates were then separated by cellulose acetate electrophoresis and the areas of the individual peaks were calculated using standard methods. As can be seen in the chromatographs and quantitated data, the second sample, which was treated with fumed silica prior to filtration, resulted in a filtrate with a much 30 higher IgG purity than the sample not treated with fumed silica (68.8% vs. 55.7 y globulin; compare Table 18 with Table 16).

76 Table 17. Quantitation of protein peaks separated by cellulose acetate electrophoresis from the Fraction 11+111 suspension clarified by addition of filter aid only prior to filtration, shown in Figure 7A. number of peak from left to right area (%) fraction 1 55J y-globulin 2 3,2 denatured protein 3 3,7 y-globulin 4 25,5 alp-globulin 5 11,9 albumin 5 Table 18. Quantitation of protein peaks separated by cellulose acetate electrophoresis from the Fraction 11+111 suspension pretreated with fumed silica and clarified by addition of filter aid prior to filtration, shown in Figure 7B. number of peak from left to right area (%) fraction 1 68.8 y-globulin 2 18.9 atP-globulin 3 12.3 albumin 10 Example 18 The present example illustrates ultrafiltration and formulation of a 20% IgG preparation suitable for subcutaneous administration. This information was gathered during production of scale-up and pre-clinical 20% IgG preparations. The process used for manufacturing of 20% lots prior to the nanofiltration step was as described above. Ultra 15 /diafiltration was improved to concentrate the solution to 20%. In order to reduce yield loss to a minimum, the post-wash of the ultrafiltration device used for diafiltration is concentrated by a second smaller device equipped with the same membranes and afterwards added to the bulk solution.

77 Surprisingly it could be shown that virus inactivation during low pH storage is not influenced by the protein concentration of the solution. Similar virus reduction was achieved in both 10% solution (GAMMAGARD* LIQUID) and in 20 % solution. Therefore low pH storage as a virus reduction step was maintained for the 20 % product. 5 Prior to nanofiltration, the glycine concentration of the IgG solution is adjusted to a target of 0.25M. The solution is then concentrated to a protein concentration of 6 ± 2 % w/v through ultrafiltration (UF). The pH is adjusted to 5.2 ± 0.2. The UF membrane used has a Nominal Molecular Weight Cut Off (NMWCO) of 50,000 daltons or less and is especially designed for high viscosity products (e.g., V screen from Millipore). 10 The concentrate is then diafiltered against a 0.25M glycine solution, pH 4.2 ± 0.2. The minimum exchange volume is 10 times the original concentrate volume. Throughout the ultrafiltration/diafiltration operation, the solution is maintained at between about 4'C to 20 0 C. After diafiltration, the solution is concentrated to a protein concentration of at least 22% 15 (w/v). The solution temperature is adjusted to 2'C to 8'C. In order to recover the complete residual protein in the system, the post-wash of the first bigger ultrafiltration system is done with at least 2 times the dead volume in re circulation mode to assure that all protein is washed out. Then the post-wash of the first ultrafiltration system is concentrated to a protein concentration of at least 22% w/v with a 20 second ultra-/ diafiltration system equipped with the same type of membrane which is dimensioned a tenth or less of the first one. The post-wash concentrate is added to the bulk solution. The second ultrafiltration system is then post-washed. This post-wash is used for adjustment of the protein concentration of the final formulation. The solution temperature is maintained at between about 2'C to 8'C. 25 In order to formulate the final solution, the protein concentration is adjusted to about 20.4 ± 0.4% (w/v) with post-wash of the second smaller ultrafiltration system and/or with diafiltration buffer. The pH is adjusted to between about 4.4 to 4.9, if necessary. It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested 30 to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims. All publications, patents, and patent 78 applications cited herein are hereby incorporated by reference in their entirety for all purposes. The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that such art forms part of the common general knowledge in Australia. 5

Claims (36)

1. A method for preparing an enriched IgG composition from plasma, the method comprising the steps of: (a) precipitating a cryo-poor plasma fraction with from about 6% to about 10% alcohol at a pH of from 7.0 to 7.5 to obtain a first precipitate and a first supernatant enriched in IgG; (b) precipitating IgG from the first supernatant with from about 20% alcohol to about 25% alcohol at a temperature of from at a pH of from 6.7 to 7.1 to form a second precipitate; (c) suspending the second precipitate to form a suspension and treating the suspension formed with finely divided silicon dioxide; (d) precipitating IgG from the suspension formed in step (c), in a third precipitation step, with from about 22% to about 28% alcohol at a pH of from 6.8 to 7.2 to form a third precipitate; (e) suspending the third precipitate to form a suspension; and (f) separating the soluble fraction from the suspension formed in step (e), thereby forming an enriched IgG composition, wherein the pH of at least one of precipitation step (a), precipitation step (b), and precipitation step (d) is achieved by addition of a pH modifying solution after addition of the alcohol.

2. The method of claim 1, wherein the wherein the alcohol concentration of precipitation step (b) is about 25%.

3. The method of claim 1 or 2, wherein the temperature of precipitation step (b) is from -7 'C to -9 'C. 80

4. The method according to any one of claims 1 to 3, wherein the precipitate formed in step (b) is suspended with from about 12 L to about 18 L of buffer per kg precipitate.

5. The method according to any one of claims 1 to 3, wherein the precipitate formed in step (b) is suspended with about 15 L of buffer per kg precipitate.

6. The method according to any one of claims 1 to 5, wherein the suspension formed in step (c) is treated with from 0.02 kg to 0.06 kg of finely divided silicon dioxide per kg of the second precipitate suspended.

7. The method according to any one of claims 1-6, wherein treatment with finely divided silicon dioxide comprises mixing the finely divided silicon dioxide with the suspension formed in step (c) for at least 30 minutes.

8. The method according to any one of claims 1 to 7, wherein the addition of a pH modifying solution comprises spray addition of the pH modifying solution.

9. The method according to any one of claims 1 to 8, wherein the pH of all of precipitation step (a), precipitation step (b), and precipitation step (d) is achieved by addition of a pH modifying solution after addition of the alcohol.

10. The method according to any one of claims 1 to 9, wherein the pH of the precipitation step is modified before and after addition of the alcohol, during and after addition of the alcohol, or before, during, and after addition of the alcohol.

11. The method according to any one of claims 1 to 10, wherein the pH of at least one of precipitation step (a), precipitation step (b), and precipitation step (d) is maintained for the entire precipitation step by continuous adjustment of the pH.

12. The method according to any one of claims 1 to 11, wherein the method further comprises an ion exchange chromatography purification step.

13. The method according to any one of claims 1 to 12, wherein the method further comprises a nanofiltration step. 81

14. The method of claim 13, wherein the nanofiltration step comprises the use of a nanofilter having a mean pore size of from 15 to 72 nm.

15. The method of claim 13, wherein the nanofiltration step comprises the use of a nanofilter having a mean pore size of about 35 nm.

16. The method according to any one of claims 1 to 15, wherein the enriched IgG composition obtained in step (f) contains at least 85% of the IgG content found in the cryo-poor plasma fraction used in step (a).

17. The method according to any one of claims 1 to 15, wherein the enriched IgG composition obtained in step (f) contains at least 90% of the IgG content found in the cryo-poor plasma fraction used in step (a).

18. The method according to any one of claims 1 to 17, wherein the purity of IgG in the final composition is at least 95%.

19. The method according to any one of claims 1 to 17, wherein the purity of IgG in the final composition is at least 98%.

20. The method according to any one of claims 1 to 17, wherein the purity of IgG in the final IgG composition is at least 99%.

21. The method according to any one of claims 1 to 20, wherein the alcohol is ethanol.

22. The method according to any one of claims 1 to 21, wherein the plasma is human plasma.

23. An aqueous composition comprising IgG, the composition prepared according to a method of any one of the preceding claims.

24. The aqueous composition of claim 23, wherein the composition comprises at least about 80 grams of protein per liter of the composition.

25. The aqueous IgG composition of claim 23 or 24, wherein at least 95% of the protein is IgG. 82

26. The aqueous IgG composition of claim 23 or 24, wherein at least 98% of the protein is IgG.

27. The aqueous composition according to any one of claims 23 to 26, wherein the composition contains less than about 35 pg/mL IgA.

28. A pharmaceutical composition comprising IgG, the composition prepared according to a method of any one of claims 1 to 22.

29. The pharmaceutical composition of claim 28, wherein the composition comprises about 100 grams of protein per liter of the composition.

30. The pharmaceutical composition of claim 28 or 29, wherein the composition further comprises glycine at a concentration from between about 200 mM to about 300 mM.

31. The pharmaceutical composition according to any one of claims 28 to 30, wherein the pH of the composition is from about 4.6 to about 5.1.

32. The pharmaceutical composition according to any one of claims 28 to 31, wherein the osmolarity of the composition is from about 240 mOsmol/kg to about 300 mOsmol/kg.

33. The pharmaceutical composition according to any one of claims 28 to 32, wherein the composition is stable at room temperature for at least 9 months.

34. The pharmaceutical composition according to any one of claims 28 to 33, wherein the composition is stable at a temperature from about 2'C to about 8'C for at least 36 months.

35. The pharmaceutical composition according to any one of claims 28 to 34, wherein the composition is formulated for intravenous administration.

36. A method of treating an immunodeficiency, autoimmune disease, or acute infection in a human in need thereof, the method comprising administering a pharmaceutical composition according to any one of claims 28 to 35.