JP5832723B2 - Standard for quantification of soluble interleukin-2 receptor - Google Patents

Description

  The present invention relates to a standard for quantification of soluble interleukin-2 receptor.

  Interleukin-2 receptor (hereinafter referred to as IL-2R) is composed of an α chain, a β chain, and a γ chain, and a soluble interleukin-2 receptor in which a part of the α chain is released from the cell. (Hereinafter referred to as sIL-2R) is known to exist in blood (see Patent Document 1 and Non-Patent Document 1). Since sIL-2R is produced by activated T cells and B cells, sIL-2R in the blood increases with the activation of the immune defense mechanism of the living body, the activation of T cell line and B cell line, etc. Has been reported. The serum sIL-2R concentration is high in patients with autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus (SLE), and viral infections such as viral hepatitis and acquired immune deficiency syndrome (AIDS), It has been reported that it becomes one of the indicators of the amount of activated lymphocytes in the body (see Non-Patent Document 2). Moreover, it is known that tumor cells produce sIL-2R, and the progression of adult T-cell leukemia (ATL) and non-Hodgkin lymphoma is well correlated with fluctuations in serum sIL-2R concentration (Non-patent Document 3, Non-patent document 4). Thus, sIL-2R has been reported to be associated with various immune system diseases and pathologies, and is recognized as a promising blood marker for hematopoietic diseases. The serum sIL-2R concentration is effectively used clinically as an indicator for pathological monitoring in adult T-cell leukemia, for non-Hodgkin lymphoma, for determining therapeutic effects, monitoring after remission, and early detection of recurrence.

  Examples of sIL-2R quantification reagents in serum or plasma include “Cell-free IL-2R Medex” (manufactured by Kyowa Medex), “Siemens Imrise IL-2R II” (manufactured by Siemens), and the like. Used in.

  When sIL-2R in serum or plasma is quantified, it is essential to prepare a calibration curve that associates the sIL-2R concentration with the measurement value, and a standard product of sIL-2R is necessary for the creation of the calibration curve.

  As a standard for sIL-2R quantification, it is necessary that sIL-2R, which is a protein, can be stably maintained for a long period of time. As a protein stabilization method, generally, a method of freeze-drying a protein is known. (See Patent Document 2). A lyophilized standard product is also known for sIL-2R [for example, a standard reagent of “Cell Free IL-2R Medex” (manufactured by Kyowa Medex Co., Ltd.]). The freeze-dried standard product requires a freeze-drying operation in the production thereof, and the production is complicated. In the case of a freeze-dried standard product, it is common to use a specified amount of purified water or solution for dissolution when preparing a calibration curve. The concentration of the standard product is likely to change due to an error in the amount or the user adding an incorrect amount. This also makes it difficult to achieve stable measurement, which affects daily measurement accuracy management.

  In addition, various methods other than freeze-drying have been reported so far for protein stabilization methods, and methods for coexisting chelating agents have also been reported (see Patent Documents 3 to 5).

JP-A 62-70761 International Publication No. 00/075189 Pamphlet Japanese Patent Laid-Open No. 10-191972 JP 2000-221190 A JP 2004-129531 A

The Journal of Immunology, vol.135, No.5, p.3172-3177 (1985). Clinical immunology and immunopathology, vol.50, No.3, p.321-332 (1989). Clinical pathology, vol.42, No.8, p.834-842 (1994). Laboratory test, vol.35, No.1, p.87-91 (1991).

  When the standard product is a solution, the manufacturing complexity is low and the measurement accuracy control is easy. However, when the solution is a solution, there is a problem that the storage stability is inferior compared with the freeze-dried standard product. . An object of the present invention is to provide a standard for sIL-2R quantification excellent in storage stability.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that sIL-2R in an aqueous solution is stably held in the presence of a chelating agent, and have completed the present invention. That is, the present invention includes the following [1] to [4].
[1] A standard for quantitative determination of sIL-2R, containing a known concentration of soluble interleukin-2 receptor (sIL-2R) and a chelating agent in an aqueous medium.
[2] The standard product according to [1], wherein the chelating agent is ethylenediaminetetraacetic acid (EDTA).
[3] A method for quantifying soluble interleukin-2 receptor (sIL-2R) in a specimen, wherein the standard product according to [1] or [2] is used.
[4] A soluble interleukin-2 receptor in a sample, comprising the standard product according to [1] or [2] and a soluble interleukin-2 receptor (sIL-2R) quantification reagent (SIL-2R) quantification kit.

  According to the present invention, a standard for sIL-2R quantification excellent in storage stability is provided.

  The sIL-2R standard of the present invention comprises known concentrations of sIL-2R and a chelating agent in an aqueous medium. The sIL-2R contained at a known concentration in the standard product of the present invention may be one produced by a gene recombination method or one collected from a biological sample. Examples of a gene recombination method used when producing sIL-2R by a gene recombination method include, for example, a method of producing sIL-2R in a transformant obtained using Escherichia coli as an host and animal cells [for example, Molecular Cloning: A Laboratory Manual 3rd. Ed. (Cold Spring Harbor Laboratory Press, New York, 2001)]. Examples of a method for collecting sIL-2R from a biological sample include a method for separating and purifying sIL-2R from a biological sample such as blood, plasma, and serum that may contain sIL-2R. Examples of methods for separating and purifying sIL-2R from biological samples include polyacrylamide electrophoresis (SDS-PAGE), gel filtration chromatography, hydrophobic chromatography, affinity chromatography (for example, “Protein Experiment Handbook” 2003, For example, see Yodosha).

  The chelating agent used in the standard product of the present invention is not particularly limited as long as it is a chelating agent that can stably hold sIL-2R in the standard product of the present invention in an aqueous medium. For example, Bicine [N, N- Bis (2-hydroxyethyl) glycine], CyDTA (trans-1,2-diaminocyclohexane-N, N, N ′, N′-tetraacetic acid), DTPA (diethylenetriamine-N, N, N ′, N ″, N ″ -pentaacetic acid), EDTA (ethylenediamine-N, N, N ′, N′-tetraacetic acid), EDDP (ethylenediamine-N, N′-dipropionic acid), EDTA-OH [N- (2-hydroxy) Ethyl) ethylenediamine-N, N ′, N′-triacetic acid], EGTA [O, O′-bis (2-aminoethyl) ethylene glycol-N, N, N ′, N′-tetraacetic acid HIDA [N- (2-hydroxyethyl) iminodiacetic acid], IDA (iminodiacetic acid), NTA (nitrilotriacetic acid), NTPO [nitrilotris (methylenephosphinic acid)], TPEN [N, N, N ′, N′-tetrakis (2-pyridylmethyl) ethylenediamine], TTHA (triethylenetetramine-N, N, N ′, N ″, N ′ ″, N ′ ″-hexaacetic acid), gluconic acid, citric acid, ADA [N- (2-acetamido) iminodiacetic acid], Tricine {N- [tris (hydroxymethyl) methyl] glycine}, Tris {N- [tris (hydroxymethyl) methyl] glycine} and the like, and EDTA preferable. These chelating agents may form hydrates and salts. Examples of the salt include sodium salt, potassium salt, calcium salt, ammonium salt, hydrochloride, sulfate, nitrate and the like.

  The concentration of the chelating agent is not particularly limited as long as it is a concentration that can stably maintain sIL-2R in an aqueous medium in the present invention, and is, for example, 0.05 to 10.0 mmol / L, preferably 0.1 -5.0 mmol / L.

  The aqueous medium used in the standard product of the present invention is not particularly limited as long as it is an aqueous medium that can stably hold sIL-2R, and examples thereof include deionized water, distilled water, and a buffer solution. Liquid is preferred. Examples of the buffer used in the buffer include a phosphate buffer, a borate buffer, a Good buffer, and the like.

  Good buffers include, for example, 2-morpholinoethanesulfonic acid (MES), Tris, bis (2-hydroxyethyl) iminotris (hydroxymethyl) methane (Bis-Tris), N- (2-acetamido) iminodiacetic acid ( ADA), piperazine-N, N′-bis (2-ethanesulfonic acid) (PIPES), N- (2-acetamido) -2-aminoethanesulfonic acid (ACES), 3-morpholino-2-hydroxypropanesulfonic acid (MOPSO), N, N-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid (BES), 3-morpholinopropanesulfonic acid (MOPS), N- [tris (hydroxymethyl) methyl] -2-amino Ethanesulfonic acid (TES), 2- [4- (2-hydroxyethyl) -1-piperazini Ethanesulfonic acid (HEPES), 3- [N, N-bis (2-hydroxyethyl) amino] -2-hydroxypropanesulfonic acid (DIPSO), N- [tris (hydroxymethyl) methyl] -2-hydroxy- 3-aminopropanesulfonic acid (TAPSO), piperazine-N, N′-bis (2-hydroxypropanesulfonic acid) (POPSO), 3- [4- (2-hydroxyethyl) -1-piperazinyl] -2-hydroxy Propanesulfonic acid (HEPPSO), 3- [4- (2-hydroxyethyl) -1-piperazinyl] propanesulfonic acid [(H) EPPS], Tricine, Bicine, N-tris (hydroxymethyl) methyl-3-aminopropane Sulfonic acid (TAPS), N-cyclohexyl-2-aminoethanesulfo Acid (CHES), N- cyclohexyl-3-amino-2-hydroxy propane sulfonic acid (CAPSO), and the like N- cyclohexyl-3-amino propane sulfonic acid (CAPS) and the like.

  As pH of a buffer solution, it is pH 4.0-10.0, and pH 6.0-8.0 are preferable. The concentration of the buffer is not particularly limited as long as sIL-2R can be stably maintained in the aqueous medium in the present invention, and is, for example, 0.005 to 1.0 mol / L, preferably 0.01 -0.1 mol / L.

  The standard product of the present invention may contain inorganic salts, sugars, proteins, preservatives, surfactants and the like. Examples of inorganic salts include sodium chloride, sodium nitrate, sodium sulfate, potassium chloride, potassium nitrate, potassium sulfate, ammonium chloride, ammonium nitrate, ammonium sulfate, magnesium chloride, magnesium nitrate, magnesium sulfate, calcium chloride, calcium nitrate, calcium sulfate, or Examples include adducts of these salts. Examples of the adduct include a hydrate.

  Examples of the saccharide include sucrose, dextran, alginic acid or a salt thereof. Examples of the protein include bovine serum albumin (BSA) and sericin. Examples of the preservative include sodium azide, bioace (manufactured by Kumiai Chemical Industry Co., Ltd.), proclin (manufactured by Sigma Aldrich Japan Co., Ltd.), proxyl (manufactured by Avicia Co., Ltd.) and the like. Examples of the surfactant include a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant.

The method for quantifying sIL-2R in a sample of the present invention is a method using the standard product of the present invention, and includes the following steps.
[1] A step of creating a calibration curve that associates the concentration of sIL-2R with the measured value using the standard product of the present invention and the reagent for quantifying sIL-2R;
[2] A step of measuring sIL-2R in the sample using the sample and the reagent for quantifying sIL-2R used in [1], and obtaining a measurement value for the sIL-2R concentration in the sample;
[3] A step of determining the sIL-2R concentration in the specimen from the measurement value obtained in the step [2] and the calibration curve created in the step [1].

  Here, the reagent for quantifying sIL-2R is not particularly limited as long as it is a reagent capable of quantifying sIL-2R, and examples thereof include an immunoassay reagent containing an antibody against sIL-2R. . Examples of commercially available reagents for sIL-2R quantification include “Cell-free IL-2R Medex” (manufactured by Kyowa Medex) and “Siemens Imrise IL-2R II” (manufactured by Siemens). The sample is not particularly limited as long as it may contain sIL-2R, and examples thereof include whole blood, serum, and plasma.

  The kit for quantifying sIL-2R of the present invention contains the standard product of the present invention and a reagent for quantifying sIL-2R. Examples of the sIL-2R quantification reagent include the sIL-2R quantification reagent described above. The kit for quantifying sIL-2R of the present invention can be used in the method for quantifying sIL-2R of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, these do not limit the scope of the present invention at all. In this example, reagents from the following manufacturers were used. In addition, sIL-2R used what was manufactured by the gene recombination method.

  Dipotassium hydrogen phosphate (phosphate buffer; manufactured by Wako Pure Chemical Industries, Ltd.), Potassium dihydrogen phosphate (phosphate buffer; manufactured by Wako Pure Chemical Industries, Ltd.), EDTA-2Na (manufactured by Dojin Chemical Laboratory), Sodium chloride (manufactured by Wako Pure Chemical Industries, Ltd.), BSA (manufactured by Proliant), sucrose (manufactured by Kanto Chemical Co., Inc.), proxyl (manufactured by Avecia).

A standard product having the following composition was prepared.
Phosphate buffer solution 10 mmol / L (pH 7.5)
sIL-2R 200 U / mL
EDTA · 2Na 0, 0.1, 1.0, 2.5, 5.0 mmol / L
Sodium chloride 150mmol / L
BSA 1%
Sucrose 0.8%
Proxyl 0.1%

A standard product having the following composition was prepared.
Phosphate buffer solution 10 mmol / L (pH 7.5)
sIL-2R 600 U / mL
EDTA · 2Na 0, 0.1, 1.0, 2.5, 5.0 mmol / L
Sodium chloride 150mmol / L
BSA 1%
Sucrose 0.8%
Proxyl 0.1%

A standard product having the following composition was prepared.
Phosphate buffer solution 10 mmol / L (pH 7.5)
sIL-2R 10800 U / mL
EDTA · 2Na 0, 0.1, 1.0, 2.5, 5.0 mmol / L
Sodium chloride 150mmol / L
BSA 1%
Sucrose 0.8%
Proxyl 0.1%

  The stability was evaluated using the standard products of Examples 1 to 3. After the standard products prepared in Examples 1 to 3 were stored at 40 ° C. for 0, 6, and 12 days, measurement was performed using a sIL-2R quantitative reagent “Cell-Free IL-2R” (manufactured by Kyowa Medex Co., Ltd.). The absorbance was determined. Next, the absorbance immediately after preparation of the standard product (40 ° C., 0 day) is defined as 100%, and the absorbance of the standard product after storage with respect to the absorbance immediately after preparation (40 ° C., 0 day) is expressed as sIL-2R in the standard product. The residual rate was calculated. Tables 1 to 3 show the absorbance and residual rate immediately after preparation (40 ° C., 0 days).

  As is apparent from Tables 1 to 3, in the standard product for sIL-2R quantification that does not contain EDTA · 2Na, the residual rate decreased to 75.2 to 88.1% when left at 40 ° C. for 12 days. The standard product containing EDTA · 2Na at a concentration of 0.1 mmol / L is 85.0-102.0%, and the standard product containing EDTA · 2Na at a concentration of 1.0 mmol / L is 84.1-98. The standard product containing 0% and EDTA · 2Na at a concentration of 2.5 mmol / L is 94.0 to 100.4%, and the standard product containing EDTA · 2Na at a concentration of 5 mmol / L is 93.4 to 103. It was found that the residual ratio of the standard product containing EDTA · 2Na was higher than that of the standard product containing no EDTA · 2Na. From the above results, it was shown that sIL-2R is stably maintained in the standard product for quantification of sIL-2R of the present invention containing EDTA · 2Na.

  Using Arrhenius's law, protein stability (lifetime) can be predicted from the temperature dependence of the chemical reaction rate. That is, storage at 40 ° C. for 6 days corresponds to storage at 10 ° C. for about 12 months, and storage at 40 ° C. for 12 days corresponds to storage at 10 ° C. for about 24 months. In the standard product for sIL-2R quantification that does not contain EDTA · 2Na, the sIL-2R amount decreases by about 12 to 25% after 24 months at 10 ° C., and accurate sIL-2R cannot be quantified. On the other hand, in the standard product containing 2.5 mmol / L of EDAT · 2Na, the decrease in the amount of sIL-2R was less than 10% at the maximum, and it was clarified that the influence on the quantification of sIL-2R was small.

According to the present invention, a standard for sIL-2R quantification excellent in storage stability is provided.

Claims (3)

Standard for sIL-2R quantification containing known concentrations of soluble interleukin-2 receptor (sIL-2R), ethylenediaminetetraacetic acid (EDTA) and bovine serum albumin (BSA) in an aqueous medium. Characterized by using the claim 1 Symbol mounting of standard, quantitative method of soluble interleukin-2 receptor in the specimen (sIL-2R). 1 SL and mounting of standard claim, soluble interleukin-2 receptor comprising a (sIL-2R) quantitative reagent, soluble interleukin-2 receptor in a sample of (sIL-2R) Quantitation kit.