WO2004050706A2

WO2004050706A2 - Regulatory t-cells

Info

Publication number: WO2004050706A2
Application number: PCT/GB2003/005279
Authority: WO
Inventors: Alexander Betz; Marinos Kallikourdis
Original assignee: Medical Research Council
Priority date: 2002-12-03
Filing date: 2003-12-03
Publication date: 2004-06-17
Also published as: AU2003285586A1; AU2003285586A8; WO2004050706A3

Abstract

The present invention relates to a sub-group of T.cells. In particular the invention relates to characteristics of regulatory T-cells which define them as such. The invention also relates to the uses of such T-cells, compositions comprising them and chemokines which recruit them in the modulation of an immune response.

Description

T-cells

The present invention relates to a sub-group of T-cells. In particular the invention relates to characteristics of regulatory T-cells. The invention also relates to the uses of such T-cells, compositions comprising them and chemokines which recruit them in the modulation of an immune response.

Chemokines (chemoattractant cytokines) were initially identified as cytokines profoundly induced by pro-inflammatory stimuli that control the recruitment of leukocytes into inflammatory foci. They are now emerging as important regulators of cellular trafficking in development and homeostasis. In addition, the chemokines also seem to be critical for the coordinated movement of dendritic cells and lymphocytes necessary to generate long lasting antigen specific immunity.

Structurally, they are small disulphide linked polypeptides of typically 60-70 amino acids long (7-lOkDa). They act at the nanomolar concentration.

The chemokine superfamily, unrecognised 10 years ago, now has over 40 different members, classified into different subfamilies on the basis of conserved structural features. Most chemokines contain four cysteine residues per monomer which are crosslinked Cysl-> Cys3 and Cys2->Cys4. The backbone of the chemokine molecule consists of beta strands while the N and C termini of the protein appear to have a less ordered structure. All chemokines for which the structure has been determined exist as non-covalently-linked dimers in solution.

The arrangement of the cysteine residues within the chemokine protein sequence forms the basis for the structural classification of chemokines. Chemokines in which the Cl and C2 cysteine residues are separated by a single amino acid are the CXC chemokines; examples include IL-8 and PF4. In CC chemokines the Cl and C2 cysteine residues are adjacent, examples include RANTES, MCP-1 (CCL2) and eotaxin. The T cell chemoattractant chemokine lymphotactin (XCLl) is the sole C chemokine with only one cysteine residue in the N terminal half of the protein. The only described CX3C chemokine is fractalkine, which has three amino acids separating Cl and C2. Fractalkine is also unusual in being the only chemokine that exists both as a membrane bound protein with the CX3C chemokine domain sitting on top of a mucin stalk and as a cleaved soluble molecule (Bazan et al.1997).

Further subdivisions of the chemokine superfamily have been made on the basis of amino acid sequence comparisons. For instance, a subgroup of CXC chemokines shares a three amino acid motif ELR (Gm-Leu-Arg) immediately preoceeding the first cysteine residue. Most of these ELR CXC chemokines bind the chemokine receptor CXCR2 and can act as neutrophil chemoattractants. A number of recently described CC chemokines have six rather than the more usual four cysteine residues and some have an extended amino terminus relative to other CC chemokines. The six-cysteine CC chemokine family includes the human chemokines 1-309 (CCL1) and Secondary Lymphoid organ Chemokine (SLC).

Chemokines mediate their effects on cells via specific cell surface receptors that contain seven transmembrane spanning regions(7TM receptors). Chemokine receptors are coupled to G proteins that transmit intracellular signals via linked phosphodiesterases. Upon binding their cognate chemokine ligands, chemokine receptors initiate changes in the intracellular concentrations of calcium and cAMP. Chemokine receptors also transmit signals to the small GTP binding proteins of the Ras and Rho families leading to rearrangement of actin bundles, pseudopod formation and cell migration.

Some chemokine receptors appear to be restricted to only limited amount of cell types eg. CCR6 is expressed on i rrmature dendritic cells and some activated T cells. Most cellular chemokine receptors bind their cognate chemokine ligands with affinities in the nanomolar range. Most chemokine receptors have multiple chemokine ligands eg. CCR4 binds Macrophage Derived Chemokine (MDC now called CCL22) and Thymus and Activation Regulated Chemokine (TARC). The Duffy antigen is a 7TM receptor expressed on erythrocytes which binds a wide range of chemokines with low affinity (Kd ~ 10-6). The Duffy receptor is thought to act as a clearance receptor for chemokines.

Chemokines are involved in the regulation of biological functions as diverse as angiogenesis, inflammation, lymphoid organ development and the orchestration of immune responses. They have been shown to be central to regulating the migration of cells of the immune system through various secondary lymphoid organs. Gene deletion models, in which chemokines or their receptors were targeted, highlight such functions although it is unclear whether the resulting phenotype is a consequence of altered lymphoid organ development or a direct effect on specific cell populations. Chemokines are thought to mediate interaction between T helper cells, effector cells and antigen presenting cells (APC), which are central to the generation of immune responses. The interaction between APC and T cells is a critical determinant of the ensuing immunological response.

Summary of the invention:

The present inventors have found that the most potent if not all regulatory T cells possess on their surface the receptor for the chemokine CCL4 named CCR5. Such an important finding has allowed the inventors to develop a method for the selection of regulatory T cells from mixtures of cells. Such a method has important therapeutic implications and cells selected using this method may be used to modulate an immune response.

Thus in a first aspect, the present invention provides a method for selecting one or more regulatory T-cells comprising the step of:

(a) Providing a population of cells comprising CD25+ T-cells;

(b) Assaying the cell population for the presence of cells which express CCR5; and (c) Selecting those T-cells which express CCR5 on their cell surface. The inventors have shown that the CCR5+ cells are a subset of CD25+ T cells. They have shown that it is the presence of the CCR5 receptor on CD25+ T cells which marks that cell as being a regulatory T cell.

Importantly, the present inventors have found that T-helper cells may also express CCR5 upon in vitro activation of these cells. Thus it is a feature of the present invention that the population of cells referred to in step (a) above is tested for the presence of CCR5 as a marker for regulatory T-cells prior to activation (preferably in vitro activation) of the cells.

In addition, the inventors have discovered that CD25+ CCR5+ regulatory T-cells may also bear the marker CD4+ or CD8+. In the case of CD4+CCR5+ regulatory T-cells the inventors have found that these cells also possess the marker Foxp3 which is a transcription factor.

Thus, advantageously, the method according to the above aspect of the invention includes the feature in step (b) that the cell population is assayed for the presence of CD4+ and Foxp3 as well as CCR5. Accordingly, advantageously regulatory T-cells according to the invention possess the markers CD4+, Foxp3 and CCR5+ as well as CD25+.

The inventors have also shown that the CD25+ CCR5+ regulatory T-cells according to the invention may also be distinguished from T-helper cells which bear CCR5 by their ability to exhibit immune suppressive activity. Thus in a further preferred embodiment of the above aspect of the invention, the method includes a further step (step (d)) which comprises testing the population of cells selected for their ability to exhibit immune suppressive activity and selecting those cells which exhibit this activity.

Regulatory T-cells were formerly known as suppressor T-cells. Thus as herein defined the term suppressor T-cell is synonymous with the term regulatory T-cell. This subgroup of T-cells plays a role in the suppression of an immune response to foreign and or self antigens. In particular regulatory T-cells function to suppress the proliferation and/or blasting of B cells and or T-cells subsequent to their activation in the presence of foreign or self antigen. The present inventors have now surprisingly found that the most potent if not all regulatory T-cells are CCR5+ and CD25+. In addition these CCR5+, CD25+ regulatory T-cells may possess the markers CD4+ or CD8+. The inventors have shown that different sub-groups of the regulatory T cells, for example CD25+. CCR5+, CD8+ cells, may have different effects on the same target cell. For example, the inventors have also surprisingly found that CD25+, CCR5+, CD8+ regulatory T-cells are effective in the suppression of the proliferation and blasting of CD8+ activated target cells. However, CD25+, CCR5+, CD8+ cells show little effect on the proliferation and blasting of CD4+ or CD 19+ activated target cells. Thus different sub-groups of regulatory T cells may have potentially varying uses.

The term 'selecting' one or more regulatory T cells refers to the process of choosing regulatory T cells from a mixture of cells. Advantageously, using the method of the above aspect of the invention, regulatory T cells will be selected from a population of cells comprising regulatory T cells and other T cells. In addition or alternatively, other cell types may be present. Those skilled in the art will appreciate that the method according to the above aspect of the invention is applicable to the selection of regulatory T cells from mixtures of any types of cells.

Populations of cells may be prepared using methods familiar to those skilled in the art, and which are described herein.

As herein defined the term 'CCR5' refers to the mouse CCR5 receptor. In addition the term as used herein includes within its scope functional analogues of the mouse CCR5 receptor. Advantageously it refers to human functional analogues of the CCR5 receptor. It should also be noted that there may be a receptor named the CCR5 receptor in humans which does not perform the same function in humans as the mouse CCR5 receptor does in mouse, and is thus not a functional analogue of the mouse CCR5 receptor. The mouse CCR5 receptor may be identified on cells using methods known to those skilled in the art and which include the use of FACs analysis, MACs sorting and the use of anti-CCR5 antibodies, particularly monoclonal anti-CCR5 antibodies. Such techniques are described herein elsewhere.

Assaying cells for the presence of CCR5 may be performed by standard laboratory techniques known to those skilled in the art and which include: the use of anti-CCR5 antibodies to detect cells expressing CCR5. Advantageously, the method involves the use of flow cytometry (FACs analysis).

The important discovery by the inventors that the cell surface component CCR5 is present on the most potent if not all regulatory T cells also provides a method for identifying such cells.

Thus, in a further aspect the present invention provides a method for identifying whether one or more T-cell/s are regulatory T-cell s comprising the steps of: (a) assaying the CD25+T-cell for the presence of CCR5 on the cell surface; and

(b) identifying a T-cell as a regulatory T cell if those one or more cells express CCR5 on their surface.

According to the above aspect of the invention the population of T-cells are assayed and cells selected prior to their activation, preferably their in vitro activation, in order to distiguish those regulatory T-cells selected from T-helper cells which bear CCR5 on their activated surfaces.

According to the above aspect of the invention, advantageously T-cells are assayed and identified as regulatory T-cells on the basis of the presence of the markers CD25+ CD4+, Foxp3 and CCR5.

According to the above aspect of the invention, the term 'assaying' means applying any test to the one or more cells as described above which tests for the presence of one or more of the cell surface markers referred to above on the surface of those one or more cells. Suitable assays involve the use of suitable antibodies in particular monoclonal antibodies, and/or the use of FACs analysis. In a further aspect still, the present invention provides a regulatory T-cell obtained by one or more of the methods of the present invention.

According to the above aspect of the invention, preferably the regulatory T-cell population possesses the markers CD25+ CD4+ Foxp3 and CCR5.

In an alternative embodiment of the invention, the regulatory T-cell population possesses the cell surface markers CD25+, CD8+, CCR5+ and exhibits imune supressive activity as described herein.

The present inventors have shown that such regulatory T cells and/or the CCR5 receptor may be used to modulate the immune response in an individual.

Thus, in a further aspect, the present invention provides a method for modulating the immune response in a vertebrate comprising the step of increasing or decreasing, or otherwise altering, the functional activity of at least one chemokine secreted by antigen presenting cells (APCs) on their activation, and which is capable of acting as a chemoattractant for the recruitment of regulatory T-cells to APCs, wherein those regulatory T cells comprise CCR5 as a cell surface component.

In an alternative embodiment of the invention, the regulatory T-cell population possesses the cell surface markers CD25+, CD8+, CCR5+ and exhibits immune supressive activity as described herein.

According to the above aspect of the invention, advantageously, at least one chemokine is CCL4 which binds to the CCR5 receptor. As referred to above CCR5+ cells will also comprise CD25 on their cell surface. According to a further aspect the present invention provides a method for modulating an immune response in a vertebrate comprising the steps of:

(a) testing one or more chemokines for their ability to be secreted by APCs on their activation, and also which are capable of acting as chemoattractant/s for the recruitment of regulatory T-cells to APCs wherein those regulatory T cells comprise CCR5 as a cell surface component.

(b) Selecting the one or more chemokines which possess the characteristics defined in step (a).

(c) Modulating the functional activity of the one or more chemokines selected according to step (b) in the vertebrate.

As referred to herein, the chemokines secreted by the activated APCs are any one or more selected from the group consisting of: CCL1, CCL4, CCL2, CCL3 and XCLl. In a preferred embodiment, the chemokine is CCL4 and/or CCL1. In a particularly preferred embodiment the chemokine is CCL4 which is a chemokine which binds to the CCR5 receptor.

The term chemokine, in the context of the present invention includes any cytokine which is involved in immune or and/or pro-inflammatory responses.

In a further aspect still the present invention provides a method for modulating an immune response in a vertebrate comprising the step of increasing or decreasing, or otherwise altering, the functional activity of the CCR5 receptor on those regulatory T- cells comprising said receptor .

According to the above aspect of the invention, the term 'increasing or decreasing or otherwise altering the functional activity of the CCR5 receptor' means increasing or decreasing or otherwise altering the functional activity of the CCR5 receptor in a proportion of those cells expressing CCR5 on their surface. Preferably it means increasing or decreasing or otherwise altering the functional activity of the CCR5 receptor in at least 10% of those cells expressing CCR5 on their surface. More preferably it means increasing or decreasing or otherwise altering the functional activity of the CCR5 receptor in at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% of those cells expressing CCR5 on their surface. Most preferably the term 'increasing or decreasing or otherwise altering the functional activity of the CCR5 receptor in a proportion of those cells expressing CCR5 on their surface' means increasing or decreasing or otherwise altering the functional activity of the CCR5 receptor in 100% of those cells expressing CCR5 on their surface.

Methods for modulating the functional activity of the CCR5 receptor will be known to those skilled in the art.

In outline, suitable methods for modulating the functional activity of CCR5 include any of those selected from the group consisting of the following: administering a pharmaceutically effective amount of CCR5 to the vertebrate; administering a pharmaceutically effective amount of one or more inhibitor/s of CCR5 to the vertebrate; modulating the transcription of CCR5 in the vertebrate; modulating the translation of CCR5 in the vertebrate; modulating the post-translational modification of CCR5 in a vertebrate and modulating the intracellular or extracellular distribution of CCR5 in the vertebrate. The skilled in the art will appreciate that this list is not intended to be exhaustive.

In yet a further aspect the present invention provides the use of a modulator of the functional activity of the CCR5 receptor in the preparation of a medicament for modulating an immune response in an vertebrate.

According to the above aspect of the invention the term 'a modulator of the functional activity of the CCR5 receptor' means a molecule which increases or decreases or otherwise alters the functional activity of the CCR5 receptor. Advantageously such a molecule is a CCR5 receptor binding molecule. Suitable molecules may be naturally occurring or synthetic. Naturally occurring molecules include proteins and polypeptides within their scope, for example antibodies which may be monoclonal or polyclonal. Those skilled in the art will appreciate that this list is not intended to be exhaustive, and will be aware of other types of molecules which may function as CCR5 functional activity modulators. Such molecules may be identified using methods known to those skilled in the art.

The term 'modulating the immune response' in the context of the present invention also includes within its scope substantially preventing or purposefully inducing autoimmunity in a vertebrate. Suitable antigen presenting cells for use in the method of the present invention include any one or more selected from the group consisting of: B cells, dendritic cells and macrophages. In a preferred embodiment of the invention, the vertebrate is a mammal.

The term 'increasing or decreasing the functional activity of at least one chemokine' in the context of the present invention includes within its scope increasing or decreasing the expression and/or intracellular or extracellular distribution, and/or activity of at least one chemokine as described herein.

Likewise the term 'increasing or decreasing the functional activity of CCR5' in the context of the present invention includes within its scope increasing or decreasing the expression, and/or activity of CCR5 as described herein.

Increasing the expression may occur as a result of increasing mRNA expression, or by increasing gene transcription using methods known to those skilled in the art. Those skilled will appreciate that there are many suitable methods to increase or decrease the expression of a nucleic acid sequence encoding a chemokine or CCR5 as herein described.

One skilled in the art will appreciate that the expression or function of one or more chemokines or CCR5 may be increased or decreased by increasing or decreasing the levels of chemokine or CCR5 mRNA respectively by post transcriptional modulation. For example, interfering RNA may be used as a method to decrease chemokine or CCR5 RNA levels. Increasing or decreasing the intracellular distribution may occur as a result of the addition of chemokine binding proteins to the intracellular environment. Alternatively, the intracellular distribution may be increased, decreased or altered by the addition or removal of signal sequences and/or leader sequences to the chemokine. Techniques used in such procedures will be familiar to those skilled in the art.

Increasing or decreasing the activity of the chemokines or CCR5 can be brought about by bringing the chemokines or CCR5 into contact with inhibitors of chemokines or CCR5, or activators of chemokines or CCR5 and/or chemokine binding molecules. The term 'contact' in the context of the present invention means does not require a physical contact. A functional contact, that is where the presence of the inhibitor or activator or chemokine binding protein affects the activity of the chemokine or CCR5, is sufficient. This may occur when, for example, a third protein mediates the interaction/contact between the chemokine binding molecule and the chemokine or CCR5. That is, the interaction is indirect.

Suitable inhibitors and activators include but are not limited to inhibitors of chemokine receptors. For example the small molecule AMD-3100 inhibits the CXCR4 receptor. One skilled in the art will be aware of other suitable inhibitors or activators. In addition co-factors or chemokine binding molecules may affect their activity. Examples include antibodies and fragments thereof (for example FAb, F(Ab')₂, Fv, disulphide linked Fv, scFv, diabody). It will be appreciated that this list is by no means exhaustive.

According to the above aspects of the invention, advantageously the functional activity of one or more chemokines and/or CCR5 is modulated using any one of more of the methods selected from the group consisting of: administering a pharmaceutically effective amount of those one or more chemokine/s to the vertebrate; administering a pharmaceutically effective amount of one or more inhibitor/s of those one or more chemokines and/or CCR5 to the vertebrate; modulating the transcription of those one or more chemokines and/or CCR5 in the vertebrate; modulating the translation of those one or more chemokines and/or CCR5 in the vertebrate; modulating the post- translational modification of those one or more chemokines and/or CCR5 in the vertebrate and modulating the intracellular or extracellular distribution of those one or more chemokines and/or CCR5 in the vertebrate.

In a preferred embodiment of this aspect of the invention, the functional activity of one or more chemokines and/or is modulated by administering a pharmaceutically effective amount of one or more inhibitor/s of those one or more chemokines and or CCR5 respectively to the vertebrate. Advantageously, the one or more inhibitor/s are selected from the group consisting of: chemical inhibitors, anti-chemokine and/or CCR5 antibodies and dominant negative mutants of those one or more chemokines and/or CCR5 respectively described herein.

The functional activity of one chemokine and/or CCR5 may be modulated, or of several chemokines and/or CCR5 may be modulated. One skilled in the art will appreciate that these chemokines may act in isolation or synergistically. In addition there may be functional redundancy in the activity of chemokines.

In a further aspect, the present invention provides the use of a chemokine which is secreted by antigen presenting cells (APCs) on their activation and which is capable of acting as a chemoattractant for the recruitment of regulatory T-cells to APCs, wherein said regulatory T-cells comprise CCR5 as a cell surface component, in the preparation of a medicament for modulating the immune response in a vertebrate.

In a preferred embodiment of the invention, the chemokines secreted by the activated APCs are any one or more selected from the group consisting of: CCL1, CCL4, CCL2, CCL3, and XCLl. In a preferred embodiment, the chemokine is CCL4 and or CCL1. In a particularly preferred embodiment, the chemokine is CCL4. According to this aspect of the invention, preferably the vertebrate is a mammal.

One skilled in the art will appreciate that chemokines according to the present invention may act independently of each other, in an additive or subtractive manner or synergistically. In addition, in a mixture of such chemokines, there may be functional redundancy. That is, one chemokine may act in preference to another chemokine in the recruitment of T cells to APCs.

APCs include the following: dendritic cells, macrophages and B cells. One skilled in the art will appreciate that the list is by no means exhaustive. Methods for their isolation will be described infra.

The present inventors have found, using methods described herein, that the chemokines of the present invention modulate the immune response via the recruitment of regulatory T-cells comprising CCR5 on their cell surface. Although the precise mechanism of recruitment is not known, it may involve the binding of CCL4 as herein defined to the CCR5 receptor as defined herein.

Thus in a further aspect the present invention provides a method for selecting those isolated regulatory T-cells which are capable of modulating an immune response in an individual comprising the step of:

(a) Providing a population of CD25+T-cells;

(b) assaying those T-cells for the presence of CCR5 on the cell surface; and

(c) selecting those T-cells which comprise CCR5 on their cell surface.

According to the further aspect of the invention, advantageously those cells selected according to the above method are then tested for their ability to exhibit immune suppressive activity (step (d)) and those cells selected.

According to the above aspect of the invention the population of T-cells are assayed and cells selected prior to their activation, preferably their in vitro activation in order to distiguish those cells selected from T-helper cells which bear CCR5 on their activated surfaces.

According to the above aspect of the invention, those cells expressing CCR5 in their cell surface also express CD25 on their cell surface. According to the above aspect of the invention advantageously the T-cells are assayed and selected on the basis of the presence of the markers CD25+, CD4+, Foxp3 as well as CCR5.

A population of regulatory T-cells, can be prepared using methods known to those skilled in the art including FACs sorting, MACsorting (sorting with magnetic beads), immunoprecipation, immunodepletion and standard chromatographic techniques. All these methods are familiar to one skilled in the art and suitable methods will be described in detail herein. Generally, the ability of a population of T-cells to migrate will be measured by techniques known to those skilled in the art, including, standard cell migration assays. Those skilled in the art will be aware of other suitable methods.

In a further aspect still, the present invention provides the use of one or more isolated regulatory T cell/s comprising CCR5 in their cell surface and which are capable of migrating towards antigen presenting cells (APCs) by chemoattraction mediated by at least one chemokine secreted by APCs on their activation, in the preparation of a medicament for suppressing an immune response in a vertebrate.

According to the above aspect of the invention, the term 'suppressing an immune response' (in a vertebrate) means suppressing a vertebrates response to foreign or self- antigens as compared with a suitable control. The suppressive affect of regulatory T- cells of the invention can be measured using methods familiar to those skilled in the art and described herein. Advantageously, the regulatory T-cells of the present invention 'suppress' an immune response by 10% as compared with a suitable control. More preferably it is suppressed by 20%, 30%, 40%, 50%, 60%, 70% as compared with a suitable control. Even more preferably the regulatory T-cells of the present invention 'suppress' an immune response by 80% or 90% as compared with a suitable control. Most advantageously, the regulatory T-cells of the present invention 'suppress' an immune response by 100% as compared with a suitable control. According to the above aspect of the invention, advantageously the chemokine is CCL4. Advantageously the mechanism of chemoattraction involves the binding of CCL4 as herein defined to the CCR5 receptor as herein defined.

According to the above aspect of the invention, preferably the CD25+, CCR5+ T-cells are in addition CD4+ , CD8+. In an especially preferred embodiment, they are CD25+, CCR5+ and CD8+ positive. In an alternative embodiment, they are CD25+ and CCR5+ and CD4+. Preferably, the chemokines will be at least one selected from the group consisting of CCLl, CCL4, CCL3, CCL2, and XCLl. More preferably, the chemokines is CCLl and/or CCL4. Most preferably the chemokine is CCL4. In a preferred embodiment of this aspect of the invention, the regulatory T-cells will be capable of migrating towards activated APC including B-cells, and/or activated T cells.

It will be appreciated that the chemokines which are functionally active according to the method of the present invention, or the regulatory T-cells may form therapeutically useful compositions.

Therefore, in a further aspect, the present invention provides a composition comprising at least one chemokine which is secreted by antigen presenting cells (APCs) on their activation, and which is capable of acting as a chemoattractant for the recruitment of regulatory T-cells to APCs, wherein the regulatory T-cells comprise CCR5 on their cell surface, or a chemokine binding molecule, and a pharmaceutically acceptable carrier, diluent or exipient.

In a preferred embodiment of this aspect of the invention, at least one chemokine is selected from the group consisting of: CCLl, CCL4, CCL2, CCL3, and XCLl. In a preferred embodiment, at least one chemokine is CCL4 or CCLl. It will be appreciated that in any composition comprising many chemokines, they may act synergistically, independently of one another, or there may be functional redundancy in the mixture. In an alternative embodiment of this aspect of the invention, the composition comprises a chemokine binding molecule. According to the above aspect of the invention, advantageously the chemokine is CCL4. Advantageously the mechanism of chemoattraction involves the binding of CCL4 as herein defined to the CCR5 receptor as herein defined.

In a further aspect still the present invention provides a composition comprising CCR5 or a CCR5 binding molecule and a pharmaceutically acceptable, diluent or exipient.

In yet a further aspect, the present invention provides a composition comprising one or more CCR5+ regulatory T-cells as herein described and a pharmaceutically acceptable carrier, diluent or exipient.

According to the above aspect of the invention, preferably the regulatory T-cells possess the markers CCR5+, CD25+, CD4+ and Foxp3.

In a further aspect, the present invention provides the use of at least one chemokine, or a composition according to the present invention in the preparation of a medicament for the prophylaxis and/or treatment of disease.

In a further aspect still the present invention provides the use of CCR5 or a modulator of the functional activity of CCR5 in the preparation of a medicament for the prophylaxis or treatment of disease.

In a further aspect still the invention provides the use of one or more isolated CCR5+ regulatory T-cells according to the invention, or a composition thereof in the preparation of a medicament for the prophylaxis and/or treatment of disease.

According to the above aspects of the invention, the regulatory T-cells may be any of those selected from the group consisting of the following: CCR5+, CD25+, CD8+; and CCR5+, CD25+, CD4+. According to the above aspects of the invention, preferably the regulatory T-cells possess the markers CCR5+, CD25+, CD4+ and Foxp3.

In the above aspect, the term 'disease' includes any one or more of the following: cancer, auto-immunity, transplant rejection, infections. It will be appreciated that the list is not exhaustive.

In a preferred embodiment of the above aspect of the invention, the cells are CCR5+, and CD25+ and CD8+; or CCR5+, CD25+, and CD4+; or CCR5+, CD25+, CD4+ and Foxp3 and the disease is transplant rejection. The CD8+ cells are found to suppress immune activated T cell proliferation but have little affect on immune activated B cell proliferation. This phenomenon is discussed in more detail in the detailed description of the invention.

Importantly the present inventors have shown that progesterone upregulates CCL4 which in turn acts as a chemoattractant for the recruitment of CCR5+ regulatory T- cells according to the invention (shown in Figs 17 and 18). Thus the inventors consider that the administration of progesterone to an individual may be used for the treatment of disease, in particular autoimmunity, transplant rejection, spontaneous abortion, pre- eclampsia and infertility.

Thus, in further aspects the invention provides:

-A method for modulating the immune response of a vertebrate comprising the step of increasing or decreasing or otherwise altering the functional activity and or the recruitment of regulatory T-cells within that vertebrate.

According to the above aspect of the invention, the in vivo modulation may be achieved by the administration of progesterone to that vertebrate.

In a further aspect the invention provides a method for the modulation of an inimune reponse within a vertebrate which comprises the steps of: (a) Isolating CD25+ CCR5- (weakly suppressive) T-cells from a vertebrate; and (b) Converting those cell isolated according to step (a) to potently suppressive CD25+CCR5+ regulatory T-cells by their in vitro treatment with any one or more agents selected from the group consisting of: anti-CD3; anti-CD154; and IL2.

(c) Introducing those cells according to step (b) into that vertebrate.

According to the above aspect of the invention, step (b) above may be substituted for step (bi) which comprises the treatment of those isolated cells above with progesterone.

According to the above aspect of the invention, the treated cells may be further enriched for CCR5 surface expression (and thus high immune suppressive function) using in vitro cell purification techniques such as FACs sorting, MACs sorting and or filtration columns.

According to the above aspect of the invention, those regulatory T-cells may be CD4+ and/or CD8+ regulatory T-cells.

In a further aspect the invention provides a method for the prophylaxis or treatment of one or more conditions selected from the following: autoimmunity, transplant rejection, spontaneous abortion, pre-eclampsia and infertility comprising the step of administering to a patient in need of such treatment a therapeutically effective amount of progesterone.

In a further aspect the invention provides the use of isolated regulatory T-cells, modulated isolated regulatory T-cells or a composition comprising them as herein described in the preparation of a medicament for the prophylaxis or treatment of one or more conditions selected from the following: autoimmunity, transplant rejection, spontaneous abortion, pre-eclampsia and infertility.

According to the above aspect of the invention the medicament also comprises a therapeutically effective amount of progesterone. -A composition comprising of one or more isolated CCR5+ regulatory T-cells modulated according to the invention and a pharmaceutically acceptable carrier, diluent or exipient.

-The use of isolated regulatory T-cells or a composition comprising them according to the invention in the preparation of a medicament for the prophylaxis or treatment of one or more conditions selcted from the following: autoimmunity, transplant reection, spontaneous abortion, pre-eclampsia and infertility.

A method for the treatment of cancer and/or infection in a vertebrate which method comprises the step of disrupting the regulatory T-cell function and or migration of regulatory T-cells as herein described within that vertebrate.

Detailed Description of the Invention:

Brief Description of the figures

Figure 1. Chemokine expression profile of primary B cells, dendritic cells and macrophages before and after stimulation (a-c) Radioautographs of arrays probed with labelled cDNA obtained from splenic B cells of MD4 transgenic mice, after the following 24h treatments (a) control, mock incubation (b) 500ng/ml hen egg lysozyme (HEL) (c) 50μg/ml LPS. A summary of the data in (a-c) is shown in (d) for direct comparison with primary data. Arrow set 1 marks the position of DNA spots of chemokines relevant to the analysis: 1: CCL22, 2: XCR1, 3: CCL2, 4: CCL3, 5: CCL4, 6:CCL5. Arrow set 2 marks the position of other genes relevant to the analysis: a: CCR6, b:CX₃CR, c:CRD6, d:PAR3, e:Igalpha, f: Igbeta. (d) Summaries of DNA array analysis of primary mouse splenic B cells (Ig^HEL transgenic/ MD4), blood B cells (wildtype, C57bl/6xBalb/c), bone marrow derived dendritic cells and peritoneal macrophages (wildtype, C57bl/6xBalb/c). In each case, cDNA preparations from control and activated cells are being compared. The stimulation used in the various cases is denoted on the left side for each particular case. Ig x-linked was by 24h treatment with lOOμg/ml anti-mouse IgM F(ab)s. Grey scale indicates degree of expression; from light grey for undetectable to black for saturated, (e) Concentration of CCL3 and CCL4 in the supernatants of control B cells (white bars) and B cells activated by Ig cross-linking (grey bars) at 24h and 48h.

Figure 2. Analysis of the migration of CD25^+ve cell from spleens of un-immunised mice, (a-f Representative examples of trans-well migration assays using T-cell column enriched primary splenic cells from Balb/c mice and 500ng/ml of the respective chemokine as chemo-attractant. Shown in red is a FACS histogram of the CD25 stained migrated cells. Each histogram contains the data from four pooled migration wells. Unstained input cells are shown for comparison in black, (a) XCLl, (b) CCL2, (c) CCL3, (d) CCL4, (e) CCL5 and (f) CCL22.

Figure 3. CCL4 attracts regulatory T cells

(a-c) Histograms of the CD4^+ve cells migrated towards specific stimuli stained for CD25 in the following trans-well migration assays (FACS gated for CD4^+ve cells only): (a) input cells, (b) cells migrated towards the supernatant of activated B cells and (c) cells migrated towards CCL4. (d) Summary of three independent migration inhibition experiments using purified T cells (approx. 90% enriched for CD4^+ve cells by depletion) prepared from three independent mice. 'Control' with RPMI; 'CCL4' using lOOng/ml; 'CCL4/alphaCCL4' using lOOng/ml pre-incubated with anti-CCL4 antibody; 'cleared' using the same concentration chemokine/antibody, but pre-cleared using Protein G sepharose; 'alphaCCL4' antibody alone. The data was normalised to the total number of cells migrated, (e) Relative expression levels of TGFbeta and CTLA-4 in splenic T cells (input) and T cells migrated towards CCL4 (migr. cells) measured with the TaqMan 5'nuclease fluorogenic quantitative PCR assay, normalised to the expression of HGPRT.

Figure 4. Accelerated germinal centre formation upon reconstitution of nu-/nu- mice with CD25 depleted T cells or injection of neutralising anti-CCL4 antibody.

Frozen spleen sections were prepared from nu-/nu- mice (a) without treatment; (b) 14 days after reconstitution with 5xl0⁶ splenic T cells; (c) 14 days after reconstitution with 5xl0⁶ splenic T cells depleted of CD25^+ve cells; (d,e) 7 days after i.v. anti-CCL4 treatment on day 0, 1 and 2 (d) without prior reconstitution with T cells and (e) after injection of 10⁶ purified splenic T cells from age and gender matched Balb/c mice. Further, frozen spleen sections were prepared from Balb/c mice 7 days after (f ) i.v. injection of anti-CCL4 antibody on day 0, 1 and 2; (g) i.p. injection of OxCSA alum precipitate plus 10⁹ Bordetella pertussis, (h) Magnified view of germinal centre of an anti-CCL4 treated animal. All sections (a-h) were stained for IgD in blue, IgGl in red and Thyl.2 in grey. The red arrows mark T cell zones, the open black arrows mark IgGl switched cells within germinal centres and the filled black arrows mark IgGl switched cells in extra-follicular foci. The results of these experiments are representative examples of at least three independent experiments in each case.

Figure 5. The effect of regulatory T cells on B cell proliferation and blasting. B cells were activated with 50μg/ml LPS and incubated with specific T cell populations, which were activated by anti-CD3 cross-linking, (a-d) FACS scatter profiles of a typical proliferation assay gated on CD4^"ve cells only; (a) control B cells, (b) B cells incubated with LPS, (c) B cells incubated with LPS and 'total' T cells (input) used in the migration assay and (d) B cells incubated with LPS and T cells migrated towards CCL4. (e and f) Summaries of three proliferation experiments each, using Calibrite Beads for accurate quantification of FACS counted cells (e) Effects of CCL4 migrated cells and input cells on the relative proliferation of B cells (shown as x-fold increase in cell number) upon LPS stimulation, (f) Effect of CD4^+ve CD25-^ve and CD4^+ve CD25^+ve cells on the relative proliferation of B cells upon LPS stimulation.

Figure 6. Anti-CCL4 treated mice develop IgG switched auto-antibodies. Serial dilutions of the blood taken from 7days after the following treatments (three animals in each group): control (open grey squares); i.p. immunisation with OxCSA at day 0 (filled black squares); i.v. anti-CCL4 treatment on days 0, 1 and 2 (open red circles); i.p. immunisation with OxCSA on day 0 followed by i.v. anti CCL4 treatment on days 0, 1 and 2 (filled red circles), (a) total IgGl serum level (b) serum level of anti-dsDNA IgG, (c) serum level of anti-myeloperoxidase IgG and (d) serum level of anti- cardiolipin IgG. Figure 7. shows a time course of the relative expression of chemokines upon B cell activation. B cells were activated by cross-linking of surface irnmunoglobulin with anti-mouse IgM F(ab)2 (15 μg/ml) to analyse the induction of chemokine expression. Supernatants were harvested at 6 hourly intervals and assayed for the presence of the chemokines CCLl, CCL3, and CCL22 by ELIS A. (+) denotes activated supernatant ; (-) supernatant of non-activated controls.

Figure 8. CCL4 preferentially attracts CCR5+ cells. Histograms showing (a-d) CD4+, (e-h) CD8+ or (i-1) CD 19+ splenic lymphocytes that migrated towards CCL4 in transwell migration assays. The cells that migrated were stained for the respective surface markers and CCR5. (a-k) show histograms of representative experiments with (a,e,i) illustrating the FACS gating used in the analysis. The specificity and the potency of the migration is proportional to the number of total cells that migrated to the chemokine (Tm), and the number of migrated cells with a cognate receptor for the chemokine (Cm). It is inversely proportional to the number of cells (Ct) with the cognate receptor present in the input population. Tm*Cm/Ct is used as an indicator of migratory specificity and chemoattractant potency of CCL4. CCR5⁺ and CCR5^" subpopulations of (d) CD4, (h) CD8 or (1) CD19 cells were assayed, for various concentrations of the chemokine (0, 100, 250 and 500ng/ml).

Figure 9. Comparison of the expression of CCR5 and CD25 on CD4⁺ and CD8⁺ cells, (a-h) Surface marker analysis of splenic T cells, (a) CD4⁺ cells were gated for the expression of CD25. (b) Expression of CCR5 on (black) total CD4⁺ cells versus (red) CD4⁺ CD25⁺ cells, (c) CD4⁺ cells were gated for the expression of CCR5. (d) Expression of CD25 on (black) total CD4⁺ cells versus (red) CD4⁺ CCR5⁺ cells, (e) CD8⁺ cells were gated for the expression of CD25. (f) Expression of CCR5 on (black) total CD8⁺ cells versus (red) CD8⁺ CD25⁺ cells, (g) CD8⁺ cells were gated for the expression of CCR5. (h) Expression of CD25 on (black) total CD8⁺ cells versus (red) CD8⁺ CCR5⁺ cells. Expression of CCR5 on CD3⁺ (i) blood and (j) spleen lymphocytes. Purified (k) CD4⁺ or (1) CD8⁺ cells were grown for 3 days with no activation (control), anti-CD3 or anti-CD3, anti-CD28 and IL4. The percentage of cells expressing (grey bars) CD25 and (white bars) CCR5 was determined by FACS . Figure 10. Regulatory effect of CD4⁺ CCR5⁺ cells on proliferation and blasting of CD4+, CD8⁺ and CD19⁺ cells. CFSE-labelled (a-e) CD4⁺, (f-j) CD8⁺ or (k-o) CD19⁺ target cells were co-cultured for 3 days with CD4⁺ CCR5⁺ or CD4⁺ CCR5^" cells. In all cases, anti-CD3 antibody was used to activate the T cells and IgM-F(ab)₂ was used to activate the B cells. The proliferation and blasting of the target cells were analysed by FACS on day 0 and day 3. (a-d, f-i and k-o) show scatter profiles of target cells from representative experiments. For the analysis the target cells were identified by virtue of their CFSE stain and only CFSE positive cells are shown, (a-d) Effects of CD4⁺ CCR5⁺ cells, on CD4⁺ target cells: (a) CD4⁺ at day 0, (b) un-activated CD4⁺ cells, (c) activated CD4⁺ cells, (d) activated CD4⁺ cells plus CD4⁺CCR5⁺ cells, (f-i) Effects of CD4⁺ CCR5⁺ cells, on CD19⁺ cells: (f) un-activated CD19⁺ cells, (g) activated CD19⁺ cells (h) activated CD19⁺ cells plus CD4⁺ CCR5^" cells, (i) activated CD19⁺ cells plus CD4⁺ CCR5⁺ cells, (k-n) Effects of CD4⁺ CCR5⁺ cells, on CD8⁺ target cells: (k) un- activated CD8⁺ cells (1) activated CD8⁺ cells (m) activated CD8⁺ cells plus CD4⁺ CCR5^" cells, (n) activated CD8⁺ cells plus CD4⁺ CCR5⁺ cells, (e, j and o) Summary of three independent co-culturing experiments showing the percent increase in cell number of CFSE-labelled (e) CD4⁺, (j) CD19⁺ and (o) CD8⁺ target cells.

Figure 11. Regulatory effect of CD8⁺ CCR5⁺ cells on proliferation and blasting of CD4+, CD8⁺ and CD19⁺ cells. CFSE-labelled (a-e) CD8⁺, (f-j) CD4⁺ or (k-o) CD19⁺ target cells were co-cultured for 3 days with CD8⁺ CCR5⁺ or CD8⁺ CCR5^" cells. In all cases, anti-CD3 antibody was used to activate the T cells and IgM-F(ab)₂ was used to activate the B cells. The proliferation and blasting of the target cells were analysed by FACS on day 0 and day 3. (a-d, f-i and k-o) show scatter profiles of target cells from representative experiments. For the analysis the target cells were identified by virtue of their CFSE stain and only CFSE positive cells are shown, (a-d) Effects of CD8⁺ CCR5⁺ cells, on CD8⁺ target cells: (a) CD8⁺ at day 0, (b) un-activated CD8⁺ cells, (c) activated CD8⁺ cells, (d) activated CD8⁺ cells plus CD8⁺CCR5⁺ cells, (f-i) Effects of CD8⁺ CCR5⁺ cells, on CD19⁺ cells: (f) un-activated CD19⁺ cells, (g) activated CD19⁺ cells (h) activated CD19⁺ cells plus CD8⁺ CCR5^" cells, (i) activated CD19⁺ cells plus CD8⁺ CCR5⁺ cells, (k-n) Effects of CD8⁺ CCR5⁺ cells, on CD4⁺ target cells: (k) un- activated CD4⁺ cells (1) activated CD4⁺ cells (m) activated CD4⁺ cells plus CD8⁺ CCR5^" cells, (n) activated CD4⁺ cells plus CD8⁺ CCR5⁺ cells, (e, j and o) Summary of three independent co-culturing experiments showing the percent increase in cell number of CFSE-labelled (e) CD8⁺, (j) CD19⁺ and (o) CD4⁺ target cells.

Figure 13. Comparison of the regulatory potential of CCR5+ and CD25+ CCR5- cells, effect of CCR5 depletion on the suppressive potential of CD4+CD25+ cells and regeneration of CCR5+ cells, (a) CFSE-labelled CD4+ CCR5- CD25- target cells were activated with anti-CD3 antibody and co-cultured for 3 days with 2% CD4+ CCR5+ or various amounts (2%-8%) of CD4+ CCR5- CD25+ cells. The proliferation of the CFSE labelled target cells was analysed by FACS on day 3. (b) CFSE-labelled CD4+ CCR5- CD25- target cells were activated with anti-CD3 antibody and co- cultured for 3 days with CD4+ CD25+ or CCR5-depleted CD4+ CD25+ cells. The proliferation of the CFSE labelled target cells was analysed by FACS on day 3. (c) In vitro regeneration of CCR5+ cells: (live) total lymphocytes were stained for CCR5, depleted by autoMACS of CCR5+ cells, and re-stained for CCR5. (dead) The experiment was repeated with cells pre-fixed with paraformaldehyde. (d) In vivo regeneration of CCR5+ cells: (input) CFSE-labelled (control) total or (depleted) CCR5 -depleted lymphocytes from spleens of Balb/c mice were stained for CCR5 and injected i.v. into matched nu-/nu- mice, (in vivo) After 3 days the splenocytes of the nu-/nu- mice that had received (control) total lymphocytes, (depleted) CCR5-depleted lymphocytes or (not shown) no injection were harvested and the CFSE+ cells were stained for CD4 and CCR5. These results suggest that potent CCR5+CD25+ regulatory T cells are generated from precursor CCR5- CD25+ T cells.

Figure 14. Up-regulation of CCR5 expression upon activation of CD25⁺ or CD25" cells., (a-f) FACS analysis and proliferation assays after in vitro culture of (a-c) CD4⁺ cells and (d-f) CD8+ cells, (a) CD4+CD25+ or (b) CD4+CD25^" were depleted of

CCR5 and cultured either without activation, or in the presence of LL2 or LL12 plus anti-CD3 and anti-CD28. After 3 days the cells were harvested, adding the same amount of CaliBRITE beads in all wells for quantification of proliferation, and stained for CD25 and CCR5. This allowed accurate assessment of the relative number of (grey bars) CD25+CCR5" cells versus (black bars) CD25+CCR5+ cells present, (c)

Suppression assay using CFSE-labelled CD4⁺ cells as targets. CCR5-depleted

CD4+CD25+ cells or CCR5-deρleted CD4+CD25" that were cultured for 1 day in the presence of IL12, antiCD3 and antiCD28 were stained for CCR5, and sorted into

CCR5 ⁺ and CCR5" subpopulations, which were then co-cultured with CD4 ⁺ CFSE- labelled targets. Proliferation was analysed by FACS after 3 days, (d-f) FACS analysis and proliferation assays after in vitro culture of CD8⁺ cells, (d) CD8⁺CD25⁺ or (e)

CD8⁺CD25" were depleted of CCR5 and cultured either without activation, or in the presence of IL2 or IL12 plus anti-CD3 and anti-CD28. After 3 days the cells were analysed as described in (a, b) for relative number of (grey bars) CD25⁺CCR5^~ cells versus (black bars) CD25⁺CCR5⁺ cells present, (n.d.) not determined due limitations of the available cell numbers, (f) Suppression assay using CFSE-labelled CD8⁺ cells as targets. CCR5-depleted CD8⁺CD25^~ that were cultured for 1 day in the presence of IL4, antiCD3 and antiCD28 were stained for CCR5, and sorted into CCR5⁺ and

CCR5^" subpopulations, which were then co-cultured with CD8⁺ CFSE-labelled targets. Proliferation was analysed by FACS after 3 days. IL4 was chosen for the

CD8⁺CD25" activation as it was marginally more potent than IL12 in inducing CCR5 up-regulation by day 1. (g, h) Quantitative RT-PCR of Foxp3 expression levels normalised to hprt expression and to total CD4⁺ cells: (g) ex vivo isolated CD4⁺,

CD8+ cells and corresponding CD25-CCR5", CD25+CCR5" and CD25+CCR5+ subpopulations. (h) in vitro activated cells: CCR5-depleted CD4⁺CD25⁺ or

CD4+CD25" cells were activated for 2 days with antiCD3, antiCD28 and EL2 or IL12 respectively and then sorted into CCR5⁺ and CCR5" subpopulations, from which RNA was extracted for the RT-PCR analysis shown. These results suggest that pro- inflammatory helper T cells can also express CD25 and CCR5 after in vitro activation. However these are not the same cells as the CCR5+ CD25+ regulatory T cells, which are (i) potently suppressive, (ii) express the gene Foxp3 (in the case of CD4+ suppressors) and (Hi) express CCR5 and CD25 prior to any activation. Figure 15. Activation of CD4+CD25+ Treg cells in the presence of co-stimulation via CD40L leads to CCR5 up-regulation and enhanced suppressive potency.

(a) Percentage of freshly isolated splenic CD4+CD25+ cells expressing CCR5 after 48h incubation in the presence of no activation or anti-CD3, anti-CD 154(CD40L) and 5ng/ml IL2. (b) Freshly isolated CD4+CD25- cells were used as targets in a proliferation assay. Proliferation is normalised to the proliferation of target cells alone (control). CD4+CD25+ or CD4+CD25- cells were added after 48h pre-incubation on anti-CD3 coated plates in the presence or absence of anti-CD 154 and 5ng/ml IL2. These results suggest that the suppressive potency and the expression of CCR5 (and thus the ability to be recruited via CCL4) of CD25+ regulatory T cells can be enhanced by stimulating the regulatory cells with anti-CD3 and/or anti-CD154 and/or IL-2.

Figure 16. Proposed CD4 and CD8 T cell lineage based on the expression of CD25 and CCR5.

There are two populations of CD25 cells in the CD4 T cell lineage. One of them marks regulatory T cells, is thymically selected and thought to be self-renewing upon stimulation in the presence of IL-2. The other represents activated helper T cells. Both CD25+ populations have CCR5+ subpopulations, which form out of the pool of CD25+ CCR5- cells. The two CD25+ populations are non-overlapping and have diametrically opposed functions. In both cases, the CCR5+ cells appear to be the 'effector' arm of the populations. The transcription factor Foxp3 is only expressed in regulatory T cells and can be used to distinguish the two populations. An analogous scenario can be observed for the CD8 T cell lineage. However, the relationship between the two CD25+ populations is not yet understood. As Foxp3 is not expressed in CD8+ cells, it cannot be used to distinguish between the regulatory and the cytotoxic population.

Figure 17. Relative expression of CCL4 mRNA in uterine tissue of pregnant versus non-pregnant mice. Uterine tissue from a mouse in diestrous (identified by vaginal smear and Giemsa staining) or a syngeneically mated pregnant mouse at day E12.5 of gestation were analysed by quantitative real-time PCR for the expression of CCL4 mRNA. These results suggest that CCL4, which can recruit CCR5+ regulatory T cells, is expressed in the uterus of pregnant females. This may enable the recruitment of CCR5+ regulatory T cells to the pregnant uterus, thereby blocking the mothers ' immune system from attacking the (semi-allogeneic) fetus. Hence immunological rejection of the fetus and pre-eclampsia are avoided.

Figure 18. Effect of progesterone on ex vivo cultured uterine tissue from a non- pregnant mouse. Uterine tissue from a non-pregnant mouse was incubated in the presence or absence of lOnM progesterone. After 4 hours RNA was isolated from the tissues and analysed by quantitative real-time PCR for the expression of CCL4 mRNA. These results suggest that progesterone, which is upregulated during pregnancy, can lead to CCL4 expression by uterine tissue. This may enable the recruitment of regulatory T cells (via CCR5-CCL4 interaction) to the pregnant uterus, thereby averting the mothers' immune system from attacking the (semi-allogeneic) fetus. Hence immunological rejection of ihe fetus and pre-eclampsia are avoided.

Figure 19. FACS analysis of CD8+ and CD4+ lymphocytes isolated from the uterus of a pregnant mouse. The lymphocytes were analysed for the expression of CCR5 and CD25. The results suggest that the vast majority of CD4+CD25+ and CD8+CD25+ cells in the pregnant uterus are CCR5+. These results suggest that the regulatory T cells present in the pregnant uterus are all potenly suppressive CCR5+ regulatory T cells. Further, they suggest that these cells may be recruited to the uterus via CCL4, which is expressed by uterine tissue (i)during pregnancy or (ii) after exposure to progesterone.

Definitions

Chemokine A chemokine in the context of the present invention includes any cytokine which plays a role in an immune response and/or pro-mflammatory response.

Examples include CCL3 (MlPlalpha), CCL4 (mip 1 beta), MJP2, CCL19 (MIP3beta),

CCL20 (MIP3 alpha), CXCL8 (IL8). Structurally, they are small disulphide-linked polypeptides of typically 60-70 amino acids (7-10kDa). They act at a nanomolar concentration. Those skilled in the art should appreciate that the reference model used herein is the mouse. In humans and other mammals the functional homologues to the chemokines herein described may have different names. It is conceivable that chemokines with different functions have been given the same name in different mammals. That is, non-functional homologues in different mammals may have same names. As herein described, the term chemokine includes within its scope functional homologues (as described above) of the chemokines herein described. Thus for the avoidance of any doubt, by way of example, the term 'CCL4' refers to the mouse chemokine CCL4 and also to functional homologues of mouse 'CCL4', advantageously it refers to the human functional homologue of CCL4.

As herein defined the term 'CCR5' refers to the mouse CCR5 receptor. In addition the term includes within its scope functional analogues of the mouse CCR5 receptor. Advantageously it refers to human functional analogues of the CCR5 receptor. It should also be noted that there may be a receptor named the CCR5 receptor in humans which does not perform the same function in humans as the mouse CCR5 receptor does in mouse, and is thus not a functional analogue of the mouse CCR5 receptor. Thus for the avoidance of any doubt the term 'CCR5' refers to the mouse CCR5 receptor and in other vertebrates the term 'CCR5' refers to the functional analogue of the CCR5 receptor. The CCR5 receptor may be identified on cells using methods known to those skilled in the art and which include the use of FACs analysis, MACs sorting and the use of anti-CCR5 antibodies, particularly monoclonal anti-CCR5 antibodies. Such techniques are described herein elsewhere.

Antibody An antibody (for example IgG, IgM, IgA, IgD or IgE) or fragment (such as a FAb, F(Ab')₂, Fv, disulphide linked Fv, scFv, diabody) whether derived from any species naturally producing an antibody, or created by recombinant DNA technology; whether isolated from serum, B-cells, hybridomas, transfectomas, yeast or bacteria).

Antigen Presenting Cell (APCs) As a first step in mounting an antibody response, foreign antigens are engulfed non-specifically by macrophages or other cells of the reticuloendothelial system. These cells include macrophages and dendritic cells. B cells can also act as antigen presenting cells, either by internalising antigen specifically via their antigen receptor or non-specifically via fluid phase uptake. These cells are collectively known as antigen presenting cells.

Functional Activity of a chemokine in the context of the present invention, refers to the function a chemokine normally performs in its native mammalian environment. These roles include mediators of chemoattraction or repulsion, mediators of cell-cell interactions and effects directly on the target cell.

T-cell recruitment In order to elicit an effective immune response in a mammal T- cells must come into contact with APCs. The attraction of T-cells by APCs is known as T-cell recruitment, and it ocurrs on activation of APCs. It is mediated via chemokines of the present invention such as CCL4, CCL3, CCLl and CCL2.

Regulatory T-cells were formerly known as suppressor T-cells. This sub-group of T- cells plays a role in the suppression of an immune response to foreign and/or self antigens. In particular regulatory T-cells function to suppress the proliferation and/or blasting of B cells and/or T-cells subsequent to their activation in the presence of foreign or self antigen. The present inventors have now surprisingly found that the most potent if not all regulatory T-cells possess CCR5 (in mouse) or the functional homologue of CCR5 (in humans and other vertebrates) on their cell surface, that is the most potent if not all regulatory T-cells are CCR5+ (in mouse) or comprise the functional homologue of CCR5 (in all other vertebrates other than mouse) and in addition CD25+. In addition these CCR5+ (or the functional homologue thereof), CD25+ regulatory T-cells may possess the markers CD4+ or CD8+. The inventors have also shown that CD25+,CD4+,CCR5+ regulatory T-cells as herein defined also bear the marker Foxp3 which is a trancription factor. Thus preferably regulatory T- cells according to the invention are CD4+CD25+CCR5+ Foxp3+. Such regulatory T cells advantageously exert immune suppressive effects on CD 19+ cells and/or CD4+ cells and/or CD8+ cells and or APCs as herein defined. In addition the regulatory T- cells of the present invention migrate towards chemokines expressed by activated B cells and/or activated APC. Advantageously regulatory T cells according to the present invention migrate towards CCL4 or the functional homologues thereof. The inventors have also surprisingly found that CD25+, CCR5+, CD8+ regulatory T-cells are effective in the suppression of the proliferation and blasting of CD8+ activated target cells (T-cells). However, CD25+, CCR5+, CD8+ cells show little effect on the proliferation and blasting of CD4+(T-cells) or CD19+ activated target cells (B-cells).

As referred to herein the term 'suppression of an immune response' refers to the suppression of an immune response to foreign and/or self antigens. In particular the term refers to the suppression of the proliferation and/or blasting of activated B cells and/or activated T-cells and/or any downstream effects subsequent to their proliferation or blasting which occurs as a result of the presence of foreign or self antigen in the vicinity of immune cells. The suppressive affect of regulatory T-cells of the invention can be measured using methods familiar to those skilled in the art and described herein. Advantageously, the regulatory T-cells of the present invention 'suppress' an immune response by 10% as compared with a suitable control. More preferably it is suppressed by 20%, 30%, 40%, 50%, 60%, 70% as compared with a suitable control. Even more preferably the regulatory T-cells of the present invention 'suppress' an immune response by 80% or 90% as compared with a suitable control. Most advantageously, the regulatory T-cells of the present invention 'suppress' an immune response by 100% as compared with a suitable control.

Activation of Antigen Presenting Cells occurs rapidly in an immune response. Once activated, APCs express more MHC class I and II, more Fc receptors and more co- stimulatory adhesion molecules. They also produce more cytokines such as IL-1, IL-6, TNFalpha and other mediators. APC activation is essential for the antigen processing and presentation necessary to elicit an immune response. Activation can be brought about by several methods including treatment with LPS (lipopolysaccharide), or cross- linking the surface with antibodies or F(ab)s, for example cross-linking the surface immunoglobulin (Ig) of B cells with anti-Ig F(ab)s. Modulating an immune response includes either enhancing or diminishing a mammals reaction to foreign or to self-antigen within the mammalian body and/or ex vivo. Advantageously, the term means at least either enhancing or diminishing a mammals reaction to foreign or to self-antigen within the mammalian body. The immune system involves a vast variety of molecules, which are capable of interacting with one another, as well as molecules which themselves are not directly involved in immune responses per se. Thus, certain interactions may be enhanced and others diminished such that apparently a mammals reaction to foreign or self antigen remains unaltered. Changes in immune responses of this sort are also contemplated according to the present invention. In, addition, modulating the immune response according to the present invention, includes within its scope the substantial prevention or purposeful induction of autoimmunity. According to the present invention, advantageously the term modulating the immune response refers to a suppression of the immune response as herein defined.

Functional redundancy There is functional redundancy in a mixture of chemokines when several chemokines have the same functional activity within a mixture.

General Techniques Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art (e.g., in cell culture, molecular genetics, nucleic acid chemistry, hybridisation techniques and biochemistry). Standard techniques are used for molecular, genetic and biochemical methods (see generally, Sambrook et al., Molecular Cloning: A Laboratory Manual, 2d ed. (1989) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. and

Ausubel et al, Short Protocols in Molecular Biology (1999) 4^th Ed, John Wiley & Sons, Inc. which are incorporated herein by reference) and chemical methods. In addition Harlow & Lane., A Laboratory Manual Cold Spring Harbor, N.Y, is referred to for standard Immunological Techniques.

Chemokines of the present invention A systematic analysis of the changes in the chemokine and related receptor expression before and after activation by physiological stimuli is performed in order to identify those chemokines involved in the recruitment of regulatory T cells to APCs. In the case of macrophages and dendritic cells LPS is used for activation. In addition, cross linking of surface Ig or antigen is used for the activation of B cells. Generally, the use of DNA array technology is employed for this purpose. Alternatively, the chemokines are detected in the supernatant of the cells by chemokine specific ELIS A.

(A) DNA Arrays Array technology and the various techniques and applications associated with it is described generally in numerous textbooks and documents. These include Lemieux et al., 1998, Molecular Breeding 4:277-289, Schena and Davis. Parallel Analysis with Biological Chips, in PCR Methods Manual (eds. M. Innis, D. Gelfand, J. Sninsky), Schena and Davis, 1999, Genes, Genomes and Chips. In DNA Microarrays: A Practical Approach (ed. M. Schena), Oxford University Press, Oxford, UK, 1999), The Chipping Forecast (Nature Genetics special issue; January 1999 Supplement), Mark Schena (Ed.), Microarray Biochip Technology, (Eaton Publishing Company), Cortes, 2000, The Scientist 14:25, Gwynne and Page, Microarray analysis: the next revolution in molecular biology, Science, 1999 August 6; Eakins and Chu, 1999, Trends in Biotechnology, 17:217-218, and also at http ://www. ene-chips.com..

The samples (for example, members of a library, or PCR products or oligonucleotides) are generally fixed or immobilised onto a solid phase, preferably a solid substrate, to limit diffusion and admixing of the samples. In particular, the samples may be immobilised to a substantially planar solid phase, including membranes and non- porous substrates such as plastic and glass. Furthermore, the samples are preferably arranged in such a way that indexing (i.e., reference or access to a particular sample) is facilitated. Typically the samples are applied as spots in a grid formation. Common assay systems may be adapted for this purpose. For example, an array may be immobilised on the surface of a microplate, either with multiple samples in a well or with a single sample in each well, or fibre optic bundles. Furthermore, the solid substrate may be a membrane, such as a nitrocellulose or nylon or polyvinylidene membrane (for example, membranes used in blotting experiments). Alternative substrates include gold, glass, plastic, or silica based substrates. The substrates may be coated with a reagent(s) for example poly-L-lysine or polyacrylamide. The samples are immobilised by any suitable method known in the art, for example, by charge interactions, or by chemical coupling to the walls or bottom of the wells, or the surface of the membrane. Other means of arranging and immobilising may be used, for example, pipetting, drop-touch, piezoelectric means, ink-jet and bubblejet technology or electrostatic application. In the case of silicon-based chips, photolithography may be utilised to arrange and fix the samples on the chip. Nomenclature has developed in the art, and is used herein, whereby the samples (for example, members of a library, or PCR products or oligonucleotides) immobilised on the array are termed probes and the sample (for example, libraries, or PCR products, or DNA, or cDNA, or RNA, or oligonucleotides) for hybridisation with the array is termed target.

The probes may be arranged by being "spotted" onto the solid substrate; this may be done by hand or by making use of robotics to deposit the sample. Array formats may be described as, for example, macroarrays, microarrays, high-density oligonucleotide arrays and microelectronic arrays.

To aid detection, targets and/or probes may be labelled with any readily detectable reporter, for example, a fluorescent, bioluminescent, phosphorescent, or radioactive reporter. Labelling of probes and targets is disclosed in Shalon et al., 1996, Genome Res 6:639-45. Arrays are based on the same steps. An array of the probe sample is constructed. The target sample is labelled. The labelled target sample is hybridised to the arrayed probe samples and the relative signals are measured.

Techniques for producing immobilised libraries of DNA molecules have been described in the art. Generally most prior art methods described how to synthesise single-stranded nucleic acid molecule libraries using, for example, masking techniques to build up various permutations of sequences at the various discrete positions on the solid substrate. U.S. Patent No. 5,837,832, the contents of which are incoφorated herein by reference, describes an improved method for producing DNA arrays immobilised to silicon substrates based on very large scale integration technology. In particular, U.S. Patent No. 5,837,832 describes a strategy called "tiling" to synthesise specific sets of probes at spatially-defined locations on a substrate which may be used to produced the immobilised DNA libraries of the present invention. U.S. Patent No. 5,837,832 also provides references for earlier techniques that may also be used.

Data analysis is also an important part of an experiment involving arrays. The raw data from a microarray experiment typically are images, which need to be transformed into gene expression matrices (tables where rows represent for example genes, columns represent for example various samples such as tissues or experimental conditions, and numbers in each cell for example characterise the expression level of the particular gene in the particular sample). These matrices have to be analysed further, if any knowledge about the underlying biological processes is to be extracted. Methods of data analysis (including supervised and unsupervised data analysis as well as bioinformatic approaches) are disclosed in Brazma and Vilo J (2000) FEBS Lett 480:17-24.

Details of some commercially available microarray formats are set out in Marshall and Hodgson, 1998, Nature Biotechnology, 16(1) 27-31.

In a particularly preferred embodiment of the invention a custom made DNA array may be used. In one example, a custom made DNA array containing probes for 29 chemokine genes as well as two additional putative chemokine genes was generated using the methods described above. Also included were probes for 61 non-chemokine related genes implicated in regulating cell migration. By a variety of means including exclusion of repetitive elements, keeping the PCR amplicons to a narrow size range, minimising cross hybridisation between highly homologous family members and by using gene specific primers during cDNA synthesis improved sensitivity and reproducibility when compared to commercially purchased gene discovery arrays was produced. As a result a robust and semi-quantitative map of chemokines and receptors expressed by B cells at various stages of maturation and during an immune response was developed. In order to identify those chemokines which are secreted by APCs on their activation and which act as a chemoattractant for the recruitment of regulatory T-cells to them, changes in the chemokine expression profile of a uniform population of B-cells were examined. That is, a uniform population of APCs was activated and then the cDNA preparations from these samples was hybridised to suitable DNA arrays described above.

(B) Preparation of a uniform population of APCs

Suitable methods for the preparation of a uniform population of APCs are generally known to those skilled in the art and include FACs sorting, MACsorting and standard chromatographic techniques as well as the use of isolated cells from trangenic animals.

a. FACs sorting

The FACS allows cells (lymphocytes) to be separated and isolated through the use of tagged antibodies or anti-immunoglobulins. The sample mixture is tunneled through a nozzle which isolates cells and charges them. At the base of the FACS, there are 2 variably charged deflection plates and cell collectors. In order to carry out FACS, the individual cells in a resting lymphocyte pool must be isolated. This is accomplished by suspending the cells in a fluid (eg., saline). This suspension of cells is then forced through a fine, high-pressure nozzle or fluidic diluting system which distributes the cells into a single- file line or flow cell (Kidd and Nicholson 229). Light is an integral part of the FACS technique. Light striking each cell is scattered. By using electronic devices that measure scattered light and fluorescence, different types of cells and their sizes can be identified. FACSs have two types of data collecting hardware: light scatter sensors and photomultiplier tubes (PMTs). The light scatter sensors measure the light that is scattered by each cell from two different angles. The forward angle light scatter sensor (FALS) gathers light scattered in the forward direction. This type of scattered light gives a clue as to a cell's size. Right angle, orthogonal, or side light scatter (SS) sensors gather light scattered at 90° from the original direction of the light source. This light reveals cell granularity, refractiveness, and the presence of intracellular structures that reflect light (Darzynkiewicz, et al. 335). Scatter sensors are useful in distinguishing cells based on the cells' different structures. Neutrophiles, for example, display more SS than lymphocytes (Kidd and Nicholson 229). In addition, different cell lineages or cells at different stages of development i.e., pre B cells versus plasma B cells) can be distinguished based on their forward and side scatters (Kantor, Merrill, and Hillson 13.1). Finally, PMTs detect fluorescent emissions from the fluorescent dyes on antibodies bound to cells or from auto-fluorescence of the cells. To collect selected cells, the cells are passed through an electric field generated by oppositely- charged plates. By changing the direction of the electric field between the plates, selected cells can be directed into precise collection areas. (Apoptosis by Flow Cytometry." Manual of Clinical Laboratory Immunology, 5th edn. Ed. Noel R. Rose, Everly Conway deMacario. James D. Folds, H. Clifford Lane, Robert M. Nakamura. Washington, D.C.: American).

b. APCs isolated from trangenic animals

In a particularly preferred method, the use of APCs isolated from transgenic animals may be employed. This has the particular advantage that all the APCs may be stimulated by the same antigen, because the APCs used are uniform in the sense that they express the same transgene. For example Ig ^HE (MD4) trangenic mice all express the same anti-hen egg lysozyme (HEL) immunoglobulin transgene and can be activated by HEL. Methods for the generation of transgenic animals are generally known to those skilled in the art and are discussed in detail in (First N, Haseltine FP. Transgenic animals. Stoneham, UK:Butterworth-Heinmann, 1991.Grosveld F, Kollias G. Transgenic animals. San Diego, California: Academic Press, 1992.)

c. Chromato graphic techniques

Details of standard chromatographic techniques for the preparation of uniform populations of APCs, are known to one skilled in the art and are detailed in (Antibodies, Harlow and Lane, Cold Spring Harbour, 1998).

(C) Activation of a uniform population of APCs Methods for the activation of APCs are known to those skilled in the art (Antibodies, Harlow and Lane, Cold Spring Harbour, 1998). Purified APCs can be activated by

LPS or by exposure to specific antigen and/or by lg cross-linking. For example Ig (MD4) B cells can be activated by hen egg lysozyme (HEL). Additionally, purified B cells from the blood of wild type mice can be activated by exposure to anti-mouse Ig F(Ab)s or LPS. It will be appreciated that the choice of ligand used to activate the purified APCs depends upon the APC sample used.

(D) Chemoattractant role of chemokines induced on APC activation

In order to identify which, out of those chemokines expressed upon APC cell activation are involved in the recruitment of regulatory T-cells, transwell migration assays can be performed using methods known to one skilled in the art, and detailed in (Antibodies, Harlow and Lane, Cold Spring Harbour, 1998). Those skilled in the art will be aware of other suitable methods.

A typical protocol is detailed below:

Migration assays are carried out in 6.5mm diameter, 5.0μm pore size polycarbonate membrane filter trans-well plates (Costar Corning). 0.6 ml RPMI medium containing the chemokine (500ng/ml) and/or antibody (2μg/ml) or supernatant of in vitro activated B cells was placed in the lower chamber. 0.1 ml of T lymphocyte suspension (lxlO⁷ cells/ml) was added to the upper filters. Following incubation at 37°C 10% CO for 3 hours the cells migrated into the lower chamber were stained with anti-CD4 PE (Pharmingen) and anti-CD25 FITC (Pharmingen) and analysed by FACS and quantified using beads.

Using the methods set out above, chemokines which are secreted by APCs on their activation, and which are capable of acting as a chemo-attractant for the recruitment of regulatory T-cells are identified. In a preferred embodiment, the chemokines are any one or more selected from the group consisting of: CCLl, CCL4, CCL3, CCL2, and XCLl. In an especially preferred embodiment, the chemokine/s are CCL4 and/or CCLl. In an especially preferred embodiment at least one chemokine which is secreted by APCs on their activation, and which is capable of acting as a chemo-attractant for the recruitment of regulatory T cells is CCL4.

Also included within the scope of the present invention are functional homologues of any one or more of the chemokines herein described.

The chemokines of the present invention comprise a narrow range of those chemokines already known in the art. These chemokines have been found, surprisingly, to modulate immune responses in a mammal, and this effect is brought about by the action of these chemokines in recruiting regulatory T-cells to APCs.

Those skilled in the art will appreciate that the chemokines as described herein may be effective in regulatory T cell recruitment in isolation, or when acting in conjunction with one or more further chemokines. That is, a given subset of chemokines may show regulatory T-cell recruitment effects whereas each chemokine in isolation may show negligible effects. Furthermore, one skilled in the art will appreciate that two or more chemokines may act synergistically in their effects. Those skilled in the art will appreciate that within a mixture of chemokines, one or several chemokines may influence the recruitment effects as herein described of one or more further chemokines within that mixture, be it by synergistic, additive, subtractive or other modulating effects.

Method for modulating the immune response using cytokines of the present invention

As herein defined 'modulating the immune response' involves either enhancing or diminishing a mammals reaction to foreign or to self-antigen within the body. One skilled in the art will appreciate that the irnmune system involves a vast variety of molecules, which are capable of interacting with one another as well as molecules which are not involved in immune responses. Thus, certain interactions may be enhanced and others diminished such that apparently a mammals reaction to foreign or self antigen remains unaltered. Changes in immune responses of this sort are also contemplated according to the present invention. In, addition, modulating the immune response includes within its scope the substantial prevention or purposeful induction of autoimmunity.

In a further aspect, the present invention provides a method for modulating the immune response in a mammal comprising the step of increasing or decreasing, or otherwise altering the functional activity of at least one chemokine secreted by antigen presenting cells (APCs) on their activation, and which is capable of acting as a chemoattractant for the recruitment of CCR5+ regulatory T-cells to APC and or increasing or decreasing or otherwise altering the functional activity or CCR5 itself.

The term the 'functional activity' of a chemokine, in the context of the present invention refers to the function the chemokine normally performs in its native mammalian environment. These may include roles such as chemoattractants, mediators of cell-cell interactions and so on.

Those skilled in the art should appreciate that the reference model used herein is the mouse. In humans and other mammals the functional homologues to the chemokines herein described may have different names. It is conceivable that chemokines with different functions have been given the same name in different mammals. That is, nonfunctional homologues in different mammals may have the same names. As herein described, the term chemokine includes within its scope functional homologues (as described above) of the chemokines herein described.

The term 'increasing or decreasing the functional activity of at least one chemokine ...and/or CCR5' in the context of the present invention includes within its scope increasing or decreasing the expression and/or activity of at least one chemokine and/or CCR5 respectively as described herein. Otherwise altering' the functional activity may result from adjusting the intracellular and/or extracellular distribution of the chemokine/s and or CCR5 respectively, or the nucleic acid encoding them. Increasing or decreasing the expression may occur as a result of increasing or decreasing mRNA expression respectively, or by increasing or decreasing gene transcription respectively using methods known to those skilled in the art. Increasing or decreasing the expression and/or functional activity of a chemokine and/or CCR5 may also be brought about via post-translational modications using methods known to those skilled in the art. Those skilled will appreciate that there are many suitable methods to increase or decrease the expression of a nucleic acid sequence.

Altering the intracellular distribution or extracellular distribution may occur as a result of the addition of nucleic acid binding molecules and/or, or chemokine binding molecules and/or CCR5 binding molecules, to the intra or extracellular environment, using techniques known to one skilled in the art.

Increasing or decreasing the activity of the chemokines and/or CCR5 can be brought about by bringing the chemokines or CCR5 into contact with inhibitors of the chemokines and/or CCR5 respectively, or activators of chemokines and/or CCR5 respectively and/or chemokine binding molecules and/or CCR5 binding molecules respectively. The term contact in the context of the present invention means does not require a physical contact. A functional contact, that is where the presence of the inhibitor or activator or chemokine/CCR5 binding protein affects the activity of the chemokine or CCR5 is sufficient.

Suitable chemokine or CCR5 binding molecules include antibodies as herein defined and chemokine or CCR5 dominant negative mutants. Antibodies may be prepared using standard laboratory techniques. Either recombinant proteins or those derived from natural sources can be used to generate antibodies. For example, the protein (or "immunogen") is administered to challenge a mammal such as a monkey, goat, rabbit or mouse. The resulting antibodies can be collected as polyclonal sera, or antibody- producing cells from the challenged animal can be immortalized (e.g. by fusion with an immortalizing fusion partner to produce a hybridoma), which cells then produce monoclonal antibodies. a. Polyclonal antibodies

The antigen protein is either used alone or conjugated to a conventional carrier in order to increases its immunogenicity, and an antiserum to the peptide-carrier conjugate is raised in an animal, as described above. Coupling of a peptide to a carrier protein and immunizations may be performed as described (Dymecki et al. (1992) J. Biol. Chem., 267: 4815). The serum is titered against protein antigen by ELISA or alternatively by dot or spot blotting (Boersma and Van Leeuwen (1994) J. Neurosci. Methods, 51: 317). The serum is shown to react strongly with the appropriate peptides by ELISA, for example, following the procedures of Green et al. (1982) Cell, 28: 477.

b. Monoclonal antibodies

Techniques for preparing monoclonal antibodies are well known, and monoclonal antibodies may be prepared using any candidate antigen, preferably bound to a carrier, as described by Arnheiter et al. (1981) Nature, 294, 278. Monoclonal antibodies are typically obtained from hybridoma tissue cultures or from ascites fluid obtained from animals into which the hybridoma tissue was introduced. Nevertheless, monoclonal antibodies may be described as being "raised against" or "induced by" a protein.

After being raised, monoclonal antibodies are tested for function and specificity by any of a number of means. Similar procedures can also be used to test recombinant antibodies produced by phage display or other in vitro selection technologies. Monoclonal antibody-producing hybridomas (or polyclonal sera) can be screened for antibody binding to the immunogen, as well. Particularly preferred immunological tests include enzyme-linked immunoassays (ELISA), immunoblotting and immunoprecipitation (see Voller, (1978) Diagnostic Horizons, 2: 1, Microbiological Associates Quarterly Publication, Walkersville, MD; Voller et al. (1978) J. Clin. Pathol., 31: 507; U.S. Reissue Pat. No. 31,006; UK Patent 2,019,408; Butler (1981) Methods Enzymol., 73: 482; Maggio, E. (ed.), (1980) Enzyme Immunoassay, CRC Press, Boca Raton, FL) or radioimmunoassays (RIA) (Weintraub, B., Principles of radioimmunoassays, Seventh Training Course on Radioligand Assay Techniques, The Endocrine Society, March 1986, pp. 1-5, 46-49 and 68-78), all to detect binding of the antibody to the immunogen against which it was immunogen must be labeled to facilitate such detection. Techniques for labeling antibody molecules are well known to those skilled in the art (see Harlow and Lane (1989) Antibodies, Cold Spring Harbor Laboratory, pp. 1-726.)

Other suitable activators or inhibitors of chemokines or CCR5 which may be of use in the method of the present invention include but are not limited to inhibitors of chemokine receptors. For example the small molecule AMD-3100 inhibits the CXCR4 receptor. One skilled in the art will be aware of other suitable inhibitors or activators.

Increasing or decreasing the functional activity of the chemokines of the present invention leads to a modulation of the recruitment of regulatory T-cells to APCs, and therefore a concomitant modulation of the immune response.

Regulatory T-cells of the present invention

In a further aspect of the present invention provides the use of one or more isolated regulatory T cell/s comprising CCR5 on their cell surface and which are capable of migrating towards antigen presenting cell/s (APCs) by chemoattraction mediated by at least one chemokine secreted by APCs on their activation, in particular CCL4, in the preparation of a medicament for suppressing an immune response in a vertebrate.

In a preferred embodiment of the above aspect of the invention, preferably the vertebrate is a human.

T cells can be isolated and purified using methods known to those skilled in the art. These include standard chromatographic methods including immunoprecipitation, immunodeletion and FACs sorting. A suitable source of T cells in the mouse model is spleens from un-immunised mice. One skilled in the art will be aware of other suitable sources of T cells. An example of a protocol for the isolation of T-cells is described below: T lymphocytes were prepared from Balb/c mice using Lympholyte M followed by a T cell column (Cedarlane Laboratories). CD4^+ve T lymphocytes enriched by negative selection using MACS reagents (Miltenyi biotech) and antibodies to CD 19, CD l ib, CD8a, CD80, CD86 and CD 16/32 (Pharmingen).

In a further aspect, the present invention provides a method for selecting one or more regulatory T-cells comprising the step of:

(a) Providing a population of cells comprising CD25+ T-cells;

(b) Assaying the cell population for the presence of cells which express CCR5; and (c) Selecting those T-cells which essentially express CCR5 on their cell surface.

Importantly, the present inventors have found that T-helper cells may also express CCR5 upon in vitro activation of these cells. Thus it is a feature of the present invention that the population of cells referred to in step (a) above is tested for the presence of CCR5 as a marker for regulatory T-cells prior to activation of the cells, preferably in vitro activation of the cells.

In addition, the inventors have discovered that CD25+CCR5+ regulatory T-cells may also bear the marker CD4+ or CD8+. In the case of CD4+CCR5+ regulatory T-cells the inventors have found that these cells also bear the transcription factor Foxp3.

Thus, advantageously, the method according to the above aspect of the invention includes the feature in step (b) that the cell population is assayed for the presence of CD4+ and Foxp3 as well as CCR5. Accordingly, advantageously regulatory T-cells according to the invention bear the markers CD4+, Foxp3 and CCR5+ as well as CD25+.

The inventors have also shown that the CD25+ CCR5+ regulatory T-cells according to the invention may also be distinguished from T-helper cells which bear CCR5 by their ability to exhibit immune suppressive activity. A population of T-cells is prepared as herein described. CCR5 may be detected on cell surface by using antibodies or other CCR5 binding agents as described above and/or by the use of FACs analysis, MACs analysis, immunoprecipitation and/or other method herein described.

The CCR5 receptor

Upon activation, B cells and professional antigen presenting cells up-regulate the expression of the chemokine CCL4. This chemokine has been shown to be a potent chemo-attractant for CD4⁺CD25⁺ regulatory T cells (Bystry et al). The chemokine receptor responsible for mediating CCL4 induced migrations remains unknown. However, binding studies have shown that the receptor CCR5 (Meyer A. et al. J Biol Chem 1996; 271: 14445-51) can bind CCL4, which make it a likely candidate. As a first step in analysing the potential role of CCR5 in the recruitment of regulatory T cells we examined whether the cells migrating towards CCL4 indeed express this receptor.

The chemokine CCL4 appears to mediate chemoattraction to cells bearing the CCR5 receptor. Although the precise mechanism of chemoattraction is not known it may occur via the direct or indirect binding of the CCR5 receptor to the chemokine CCL4.

One skilled in the art will appreciate that the receptor and chemokine nomenclature used throughout is mouse nomenclature. Thus as herein defined the term CCR5 includes within its scope functional analogues of CCR5. Advantageously it refers to human functional analogues of CCR5. It should also be noted that there may be a receptor named the CCR5 receptor in humans which does not perform the same function in humans as the mouse CCR5 receptor does in mouse, and is thus not a functional analogue of the mouse CCR5 receptor.

The mouse CCR5 receptor may be identified on cells using methods known to those skilled in the art and which include the use of FACs analysis, MACs analysis and the use of anti-CCR5 antibodies, particularly monoclonal anti-CCR5 antibodies. Such techniques are described herein elsewhere.

Characteristics ofCCR5+ T-cells according to the invention

Regulatory T-cells were formerly known as suppressor T-cells. This sub-group of T- cells plays a role in the suppression of an immune response to foreign and/or self antigens. In particular regulatory T-cells function to suppress the proliferation and/or blasting of B cells and/or T-cells subsequent to their activation in the presence of foreign or self antigen.

The present inventors have now surprisingly found that the most potent if not all regulatory T-cells possess CCR5 on their cell surface, that is, the most potent if not all regulatory T-cells are CCR5+ and CD25+. In addition these CCR5+, CD25+ regulatory T-cells may possess the markers CD4+ or CD8+.

Importantly, the present inventors have found that T-helper cells may also express CCR5 upon in vitro activation of these cells. Thus it is a feature of the present invention that the population of cells referred to in step (a) above is tested for the presence of CCR5 as a marker for regulatory T-cells prior to activation, preferably in vitro activation of the cells.

In addition and as described above, the inventors have discovered that CD25+CCR5+ regulatory T-cells may also bear the marker CD4+ or CD8+. In the case of CD4+CCR5+ regulatory T-cells the inventors have found that these cells also bear the marker Foxp3. Accordingly, advantageously regulatory T-cells according to the invention bear the markers Foxp3 trancription factor, cell surface marker CD4+ and CCR5+ as well as CD25+.

The inventors have also shown that the CCR5+ regulatory T-cells according to the invention may also be distinguished from T-helper cells which bear CCR5 by their ability to exhibit immune suppressive activity. The experiments shown in figure 8 indicate that CCL4 preferentially attracts CCR5+ cells. The relationship between CD25 and CCR5 on regulatory T-cells was then investigated. The results indicate that not all CD25+ cells comprise CCR5, however all CCR5+ cells are also CD25+. That is, CCR5+ cells are a subset of CD25+ cells. These results are shown in fig 9.

Further studies indicate that these sub-groups of regulatory T-cells perform the same role as CD25+ cells but significantly more effectively. In fact these studies suggest that it is the CCR5 positive cells which perform the immune suppressive role of CD25+ T cells. Further studies indicate that sub-groups of regulatory T cells may affect the same cell type differently with respect to the suppression of an immune response in that activated cell type (as judged by the levels of proliferation and blasting exhibited by these activated cells in the presence of regulatory T-cells).

Significantly, the inventors have also surprisingly found that CD25+, CCR5+, CD8+ regulatory T-cells are effective in the suppression of the proliferation and blasting of CD8+ activated target cells. However, CD25+, CCR5+, CD8+ cells show little effect on the proliferation and blasting of CD4+ or CD19 positive activated target cells. These results are shown in fig 10 and fig 11.

The results depicted in fig 13 show that it is the presence of CCR5 on T cells which results in the immune suppressive affect of T-cells on activated target cells. Specifically, the results indicate that a 2% mix of CD25+, CD4+, CCR5+ T cells at a 1:50 ratio suppresses the proliferation and blasting of activated target cells more than CD25+, CD4+ cells lacking CCR5 at a 1:12.5 ratio.

Use of chemokines, CCR5+-CD25+T-regulatory cells and compositions of the present invention In a further aspect, the present invention provides a composition comprising at least one chemokine, or chemokine binding protein, according to the present invention, and a pharmaceutically acceptable carrier, diluent or exipient. In a further aspect still, the present invention provides a composition comprising CCR5 or a CCR5 binding protein and a pharmaceutically acceptable carrier, diluent or exipient.

In yet a further aspect, the present invention provides a composition comprising at least one or more CCR5+ regulatory T cells as herein described, and a pharmaceutically acceptable carrier, diluent or exipient.

Chemokines, chemokine binding proteins, CCR5 binding proteins, CCR5+ T-cells and compositions according to the present invention may be employed in in vivo therapeutic and prophylactic applications, in vitro and in vivo diagnostic applications, in vitro assay and reagent applications, and the like.

Therapeutic and prophylactic uses of chemokines, CCR5 binding proteins, chemokine binding proteins, T-cells and compositions prepared according to the invention involve the administration of the above to a recipient mammal, such as a human.

Substantially pure chemokines, CCR5, or binding proteins of either CCR5 or chemokines of the present invention of at least 90 to 95% homogeneity are preferred for administration to a mammal, and 98 to 99% or more homogeneity is most preferred for pharmaceutical uses, especially when the mammal is a human. Once purified, partially or to homogeneity as desired, the chemokines, binding proteins and T-cells may be used diagnostically or therapeutically (including extracorporeally) or in developing and performing assay procedures using methods known to those skilled in the art.

The selected chemokines, or chemokine or CCR5 binding proteins thereof, or T-cells of the present invention will typically find use in preventing, suppressing or treating inflammatory states, allergic hypersensitivity, cancer, bacterial or viral infection, and autoimmune disorders (which include, but are not limited to, Type I diabetes, multiple sclerosis, rheumatoid arthritis, systemic lupus eryfhematosus, Crohn's disease and myasthenia gravis), and in preventing transplant rejection. For instance, depletion of the regulatory T cells or interference with their recruitment may result in an enhanced immune response which may be of particular use in the treatment of infections which otherwise escape a normal immune response. In contrast, the additional administration of regulatory T cells of the present invention may result in a dampened immune response or even complete suppression of an immune response. This could be desirable in the context of organ transplantation. In contrast, the depletion of chemokines of the present invention, for instance using anti-chemokine antibodies may lead to the generation of an autoimmune response, which may be of use in the destruction of certain cells types. This may be of particular use in the treatment of cancer.

In addition, the chemokines or regulatory T cells as herein described, may be useful for modulating a immune response in regions of a vertebrate where they are not normally located. For example, one or more chemokines used as herein described may be perfused, injected, or the nucleic acid encoding them expressed within a tissue of a vertebrate, using techniques known to those skilled in the art. The presence of a chemokine and/or a CCR5+ regulatory T-cell as described herein, in such an ectopic environment may be useful in the modulation of an immune response during for example, transplant rejection and the like.

In particular the present inventors have found that subgroups of CCR5+ regulatory T- cells have varying affects on the same target activated cell. Thus, for example CCR5+, CD8+ regulatory T-cells suppress the proliferation of activated CD8+ cells (T-cells), but have little affect on CD4+ cells (T cells), or CD 19+ cells (B-cells) (fig 11). Thus cells of this sort may be particularly effective in suppressing transplant rejection which may beT-cell mediated.

In the instant application, the term "prevention" involves administration of the protective composition prior to the induction of the disease. "Suppression" refers to administration of the composition after an inductive event, but prior to the clinical appearance of the disease. "Treatment" involves administration of the protective composition after disease symptoms become manifest.

Animal model systems which can be used to screen the effectiveness of the selected chemokines, or binding proteins thereof, or T-cells of the present invention in protecting against or treating the disease are available. Methods for the testing of systemic lupus erythematosus (SLE) in susceptible mice are known in the art (Knight et al. (1978) J. Exp. Med., 147: 1653; Reinersten et al. (1978) New Eng. J. Med., 299: 515). Myasthenia Gravis (MG) is tested in SJL/J female mice by inducing the disease with soluble Ac R protein from another species (Lindstrom et al. (1988) Adv. frnmunol., 42: 233). Arthritis is induced in a susceptible strain of mice by injection of Type π collagen (Stuart et al. (1984) Ann. Rev. Immunol., 42: 233). A model by which adjuvant arthritis is induced in susceptible rats by injection of mycobacterial heat shock protein has been described (Van Eden et al. (1988) Nature, 331: 171). Thyroiditis is induced in mice by administration of thyroglobulin as described (Maron et al. (1980) J. Exp. Med., 152: 1115). Insulin dependent diabetes mellitus (IDDM) occurs naturally or can be induced in certain strains of mice such as those described by Kanasawa et al. (1984) Diabetologia, 27: 113. EAE in mouse and rat serves as a model for MS in human. In this model, the demyelinating disease is induced by administration of myelin basic protein (see Paterson (1986) Textbook of

]-tnmunopathology, Mischer et al., eds., Grune and Stratton, New York, pp. 179-213; McFarlin et al. (1973) Science, 179: 478: and Satoh et al. (1987) J. Immunol., 138: 179).

Generally, the selected chemokines, or chemokine or CCR5 binding proteins thereof, or T-cells of the present invention will be utilised in purified form together with pharmacologically appropriate carriers. Typically, these carriers include aqueous or alcoholic/aqueous solutions, emulsions or suspensions, any including saline and or buffered media. Parenteral vehicles include sodium chloride solution, Ringer's dextrose, dextrose and sodium chloride and lactated Ringer's. Suitable physiologically- acceptable adjuvants, if necessary to keep apolypeptide complex in suspension, may be chosen from thickeners such as carboxymethylcellulose, polyvinylpyrrolidone, gelatin and alginates.

Intravenous vehicles include fluid and nutrient replenishers and electrolyte replenishers, such as those based on Ringer's dextrose. Preservatives and other additives, such as antimicrobials, antioxidants, chelating agents and inert gases, may also be present (Mack (1982) Remington's Pharmaceutical Sciences, 16th Edition).

The selected chemokines, or binding proteins thereof, or T-cells of the present invention may be used as separately administered compositions or in conjunction with other agents. These can include various immunotherapeutic drugs, such as cylcosporine, methotrexate, adriamycin or cisplatinum, and immunotoxins. Pharmaceutical compositions can include "cocktails" of various cytotoxic or other agents in conjunction with the chemokines, or binding proteins thereof, or T-cells of the present invention or even combinations of selected chemokines, or binding proteins thereof, according to the present invention.

The route of administration of pharmaceutical compositions according to the invention may be any of those commonly known to those of ordinary skill in the art. For therapy, including without limitation immunotherapy, the selected antibodies, receptors or binding proteins thereof of the invention can be administered to any patient in accordance with standard techniques. The administration can be by any appropriate mode, including parenterally, intravenously, intramuscularly, intraperitoneally, transdermally, via the pulmonary route, or also, appropriately, by direct infusion with a catheter. The dosage and frequency of administration will depend on the age, sex and condition of the patient, concurrent administration of other drugs, counterindications and other parameters to be taken into account by the clinician.

The selected chemokines, or CCR5 or their binding proteins or chemokine binding proteins, of this invention can be lyophihsed for storage and reconstituted in a suitable carrier prior to use. Known lyophilisation and reconstitution techniques can be employed. It will be appreciated by those skilled in the art that lyophilisation and reconstitution can lead to varying degrees of functional activity loss and that use levels may have to be adjusted upward to compensate.

The compositions containing the present selected chemokines, or binding proteins thereof, or T-cells of the present invention or a cocktail thereof can be administered for prophylactic and/or therapeutic treatments. In certain therapeutic applications, an adequate amount to accomplish at least partial inhibition, suppression, modulation, killing, or some other measurable parameter, of a population of selected cells is defined as a "therapeutically-effective dose". Amounts needed to achieve this dosage will depend upon the severity of the disease and the general state of the patient's own immune system, but generally range from 0.00005 to 5.0 mg of selected chemokine or chemokine binding-protein per kilogram of body weight, with doses of 0.0005 to 2.0 mg/kg/dose being more commonly used. For prophylactic applications, compositions containing the present selected polypeptides or cocktails thereof may also be administered in similar or slightly lower dosages.

A composition containing one or more selected chemokines, or CCR5 or chemokine binding proteins thereof, or T-cells according to the present invention may be utilised in prophylactic and therapeutic settings to aid in the alteration, inactivation, killing or removal of a select target cell population in a mammal. In addition, the selected repertoires of polypeptides described herein may be used extracorporeally or in vitro selectively to kill, deplete or otherwise effectively remove a target cell population from a heterogeneous collection of cells. Blood from a mammal may be combined extracorporeally with the selected antibodies, cell-surface receptors or binding proteins thereof whereby the undesired cells are killed or otherwise removed from the blood for return to the mammal in accordance with standard techniques.

CCR5+ regulatory T cells isolated from a patient may be enriched by migration and/pr FACsorting and/or MACsorting and/or immunodeletion . In addition, or alternatively these cells may be treated such that their responsiveness to one or more chemokines is modulated. Such cells may subsequently introduced into the same or a different patient. Also contemplated herein is the adoptive transfer of ex vivo enriched CCR5+ regulatory T cells from the patient him/herself or a donor.

The invention is further described, for the purposes of illustration only, in the following examples which are in no way limiting of the invention.

Examples

Example 1

During the B cell developmental program the expression of some chemokines changes. Whilst some of these changes can be deduced from studies performed with the affimetrix oligonucleotide expression array (R Glynne et al, Nature 403, 672-6 (2000)), a systematic analysis of changes in the chemokine and related receptor expression during B cell differentiation, after B cell activation and during cell-cell interaction had not until no^b en performed. For this purpose the present inventors developed a custom made DNA array containing probes for 29 chemokine genes as well as two additional putative chemokine genes. Also included were probes for 61 non-chemokine related genes implicated in regulating cell migration. By a variety of means including exclusion of repetitive elements, keeping the PCR amplicons to a narrow size range, minimising cross hybridisation between highly homologous family members and by using gene specific primers during cDNA synthesis improved sensitivity and reproducibility when compared to commercially purchased gene discovery arrays was produced. As a result a robust and semi-quantitative map of chemokines and receptors expressed by B cells at various stages of maturation and during an immune response was developed. The results are shown in (Fig 1 a-d).

Example 2

Our focus was the role of chemokines in the recruitment of T cell help during the initiation of a primary immune response. At this point, only very few B cells carry an antigen receptor that can bind a specific antigen. These B cells have to recruit T cell help in order to proliferate and differentiate. In contrast to wild type mice, all B cells from Ig^HEL (MD4) transgenic mice can be stimulated by the same antigen, since they all express the same anti-hen egg lysozyme (HEL) immunoglobulin transgene. The use of transgenic mice enabled the present invention to examine changes in the chemokine expression profile of a uniform population of splenic B cells upon stimulation with a specific antigen. Purified splenic B cells from Ig^HEL transgenic mice were stimulated for 24-48h with HEL. Alternatively, splenic B cells from wild-type Balb/c mice were stimulated with either anti mouse Ig F(ab)s or LPS. Similarly, purified B cells from the blood of C57/B16 mice were stimulated for 24-48h with either lOOμg/ml anti mouse Ig F(ab)s or LPS. B lymphocytes were prepared from the spleen of Ig^HEL transgenic (MD4) mice or blood of C57B16xBalb/c mice using Lympholyte M or Mammal, followed by a B cell column (Cedarlane Laboratories). The cells were activated for 24 hours using either 500ng/ml of hen egg lysozyme (Sigma) or 50μg of anti-mouse IgM F(ab)₂ (Jackson labs). Macrophages were harvested by peritoneal lavage and further enriched by adhesion to tissue culture plates. Bone-marrow-derived dendritic cells obtained as described [K. Inaba, et al. J. Exp. Med. 76, 1693 (1992)]. Both APC types were activated with 250ng/ml LPS (Sigma). The cDNA preparations obtained from these samples were hybridised to the DNA arrays. Approximately lng of each PCR amplicon was spotted onto Hybond N+ nylon membrane (Amersham), denatured on and then cross-linked to the membrane. The cytoplasmic RNA from 10⁶ cells was reverse transcribed using (α³²P) dATP (Amersham) and a mix of gene specific primers. After removal of unincorporated nucleotides by G50 sephadex column centrifugation, the probe was denatured and then added directly to the 'Expresshyb' solution (Clontech)/100μg herring sperm DNA, in which the blot was pre-hybridised for lhr. Hybridised for 12h at 68°C under constant agitation, was followed by four 30 minute washes in 2xSSC, 1%SDS, and one wash in O.lxSSC, 0.5% SDS at 68°C. Nomenclature of chemokines and chemokine receptors is used according to [A. Zlotnik and O.Yoshie, Immunity 12, 121 (2000)].

CCL5 is the only chemokine detected in un-stimulated splenic B cells (Fig. la, d), while un-stimulated blood B cells also express CCLl 8 and CXCL4, suggesting a possible functional difference (Fig. Id). Stimulation with antigen (Fig. lb, d), or cross- linking of surface Ig (Fig.ld), but not stimulation with LPS (Fig.lc, d) leads to down regulation of CCLl 8 and CXCL4 in blood B cells and less markedly of CCL5 in both populations. Antigen activation and Ig cross-linking but not LPS activation leads to a marked induction of CCL3 and CCL4 in both cell populations (Fig.lc, d). In splenic B cells CCL2, CCL22 and XCLl are also up-regulated. All the other 26 chemokines remain unaffected by both specific and unspecific stimulation. To confirm the expression data obtained from our DNA arrays we performed ELISA assays for CCL3 and CCL4 using supernatant derived from either non-activated or surface Ig cross- linked B cells. High levels of both chemokines can be detected upon B cell activation (Fig.le).

Example 3

In order to focus on chemokines likely to play a recruitment role early in an immune response we then enquired whether other antigen presenting cell types show a similar activation dependent chemokine/chemokine receptor profile. We therefore studied the changes in chemokine expression in macrophages and in vitro cultured dendritic cells upon activation with LPS. We found three of the five chemokines up-regulated in activated B cells (CCL2, CCL3 and CCL4) are also induced upon activation of dendritic cells and macrophages (Fig.ld). CCL22, which is only slightly induced upon activation in B cells and could not be detected in macrophages, appears to be constitutively present in dendritic cells with a further increase in expression upon activation. Further, both macrophages and dendritic cells appear to constitutively express CCL9/10 and the putative chemokine nap212. CCLl 7 can only be detected in dendritic cells whilst CCL20 can only be detected in macrophages.

To elucidate the chemoattractant role of the chemokines induced by B cell activation transwell migration assays were performed. Migration assays were carried out in 6.5mm diameter, 5.0μm pore size polycarbonate membrane filter trans-well plates (Costar Corning). 0.6 ml RPMI medium containing the chemokine (500ng/ml) and/or antibody (2 μg/ml) or supernatant of in vitro activated B cells was placed in the lower chamber. 0.1 ml of T lymphocyte suspension (lxlO⁷ cells/ml) was added to the upper filters. Following incubation at 37°C 10% CO₂ for 3 hours the cells migrated into the lower chamber were stained with anti-CD4 PE (Pharmingen) and anti-CD25 FITC (Pharmingen) and analysed by FACS and quantified using beads. Purified splenic T cells from un-primed mice were used as input cells and it was found that all five chemokines attract T cells in a concentration dependant manner (Fig. 2a). This observation is consistent with previously published data showing all 5 chemokines can function as chemo-attractants. Taken together with our data this suggests that either these chemokines act in concert to provide an integrated signal or there is significant functional redundancy. However, there are indications that some chemokines can fulfil specialized functions, not necessarily associated with cell migration. For example MCP-1 has been demonstrated to play a major role in the polarisation of the immune response (L Gu et al, Nature 404, 407-8 (2000)). hi contrast, XCLl was found to be an inhibitor of T-cell proliferation (C Cerdan et al, Blood 96 (420-8) (2000)).

Example 4

The present inventors were interested in the signals that promote cell-cell interaction at the initiation of an immune response. Therefore a more detailed analysis of cell migration induced by chemokines that show activation dependent expression in B cells and professional APC (Fig.2b-g) was performed. Using T cells purified from spleens of un-immunised mice it was observed that CCL4 induced the migration of a substantial population of CD25^+ve cells (Fig.2e). This was somewhat surprising since the number of CD25^+ve activated T cells in an un-immunised mouse spleen would be expected to be low. Furthermore, it was found that the other chemokines whose expression is activation dependent in B cells also can recruit CD25^+ve cells albeit with markedly reduced efficiency (Fig2b-g). CCL22 and XCLl are comparably poor at attracting T cells in general (Fig.2a,b,g).

Example 5 Further characterisation of the population migrating in response to CCL4 showed that almost all the CD4^+ve T cells that migrate in response to CCL4 are CD25^+ve (Fig. 3c). In keeping with the fact that the input cells were derived from un-immunised mice the migrated CD25^+ve cells were almost exclusively un-blasted. Using trypan blue and propidium iodide exclusion we confirmed that at least 80% of these distinctive cells were viable, a figure comparable with viability in the total primary cell population. In addition, real-time RT-PCR revealed that the migrated population of cells preferentially expressed TGFβ or CTLA-4 in comparison to input cells (Fig. 3e) Total RNA was prepared using an RNeasy kit (Qiagen) followed by DNasel treatment (Gibco BRL). cDNA was made using Superscripffl with random hexamer primers (Gibco BRL). Real time PCR was performed using Taqman universal PCR master mix (Applied Biosystems), VIC labelled probe for HPRT and FAM labelled probe for TGFβ or CTLA-4. An ABI prism 7700 sequence detection system was used for 45 cycles of PCR. All PCR's were set up at least in triplicate.

Expression of these proteins and an inability to respond to anti-CD3 stimulation are cardinal features of regulatory T cells. We were able to confirm that in contrast to CD4^+ve CD25^"ve cells, the CD4^+ve CD25^+ve could not be stimulated by CD3 cross- linking confirming that they are indeed anergic. Similarly, the CD4^+ve CD25^+ve cells migrating to CCL4 are anergic. This coupled with the fact that depletion of CD25^+ve cells from the input population led to a loss of CD4^+ve migrated cells makes it unlikely that CCL4 non-selectively attracts T cells and subsequently activates them, leading to expression of CD25 and CTLA4. Significantly, migration assays performed using the same input cells and supernatant of in vitro activated B cells confirms that antigen triggered B cells can recruit these distinctive CD4^+v7CD25^+ve T cells (Fig. 3b). Our results indicate that CCL4 and possibly to a lesser extent the other chemokines, might regulate the B cell mediated immune response by the recruitment of regulatory T cells. Given the role of regulatory T cells in suppressing cytotoxic T cell auto-reactivity, the recruitment of regulatory T cells by APC via these chemokines could be a general mechanism for regulating immune responses and preventing autoimmunity..

Example 6 The present inventors found that B cells and by implication professional APC can attract regulatory T cells through CCL4. It was therefore enquired whether regulatory T cells can influence a normal B cell immune response by reconstituting nu-/nu- mice with either CD25 depleted T cells or all T cells.

In a normal spleen most of the circulating B cells can be found in primary follicles adjacent to the T cell rich peri-arteriolar lymphoid sheets (PALS). Upon antigenic stimulation a few antigen specific B cells become activated and start to rapidly divide to form either germinal centres (GC) within some of the follicles or PALS associated foci. The latter can be detected by three to four days after immunisation and increase in cell number to around day 10 post-immunisation with B cells present as loose clusters of cells amongst the T cells; by day 6 they mostly consist of lymphoblasts and plasmacytes (G Kelsoe Adv hnmunol 60, 267-88 (1995)). The structure of germinal centres is somewhat more dynamic and complex. Germinal centres can be detected by day 6-7 when they are characterised by displacement of small, non-dividing IgD^+ve, PNA¹⁰ foUicular B cells by the rapidly proliferating IgD^"ve, PNA^hl blasts. The germinal centres reach their maximal size after day 12 when they are clearly divided into a dark zone containing rapidly dividing centroblasts and a light zone containing non-dividing centrocytes. Auto-reactive B cells are thought to be selectively deleted at this stage because they fail to recruit T cell help (Cyster et al, Nature 371, 389-395 (1994)). Regulatory T cells have been shown to prevent auto-reactive cytotoxic T cell mediated responses and depletion of these cells results in the generation of auto-antibodies (Takahashi et al, frit Immunol 10, 1969-80 (1998)). All these features have been attributed to an effect by regulatory T cells on other T cells. Our data suggest that activated B cells and by implication professional APC, can attract regulatory T cells via chemokines common to all three cell types. Therefore the effect of regulatory T cell depletion on the humoral immune response was studied.

The T cell compartment of nu-/nu- mice was reconstituted with either 'total' T cells or with T cells depleted of their CD25 expressing sub-populations. The transferred cells were obtained from age, gender and background matched Balb/c mice. T lymphocytes from the spleen of Balb/c mice were prepared using Lympholyte M followed by a T cell column (Cedarlane Laboratories). CD25+ cells were depleted by FACsorting. nu- /nu- mice were injected i.v with 5x10 -10 'total' T cells or CD25 depleted T cells. For the temporal depletion of CCL4, mice were injected i.v. with lOμg of either affinity purified neutralising anti-CCL4 serum or control goat serum (R&D Systems) on the first three days of the experiment. Standard OxCSA immunisation was performed by i.p. injection of lOOμg of oxazolone-chicken serum albumin alum precipitate plus 10⁹ Bordetella pertussis. The spleens were harvested seven days after the first anti-CCL4 treatment. Spleens were embedded in OCT (R.A. Lamb). Cryogenic sections (lOμm) were mounted on Vectabond (Vector labs) coated slides incubated at 56°C for 2 hrs and stored at -80°C. Frozen slides were thawed, fixed in acetone for lOmins, air dried and re-hydrated in PBS for lOmins. Sections were blocked with 10% FCS/PBS. Biotinylated antibodies were applied to sections in 5% FCS/PBS. ABC-AP or ABC-HRP (Vector Labs) were incubated for 15mins followed by washing, and final staining by Vector Labs AP or HRP staining kits. Vector Red, DAB, Vector Blue and Vector NovaRed were used. All sequential stains were carried out in one day. Before mounting with Vectamount (Vector Labs) the sections were cleared using 100% ethanol and allowed to air dry. All Vector labs products were used according to the manufacturers instructions. When mice are reconstituted with CD25 depleted T cells found an abundance of germinal centres all of which contained a substantial number of IgGl switched cells were found (Fig.4c). In addition, a dramatic increase in IgGl switched cells was found in extra follicular areas (Fig. 4c). In contrast to this, few germinal centres were seen in mice reconstituted with total T cells and these never contained any IgG switched cells (Fig.4b). However, it is clear that reconstitution with total T cells alone can cause inconsistent but usually low level switching of B cells to IgGl in the spleen (Fig. 4b). This effect is transient with a return to normal levels after 3 weeks. Consistent with this, switching induced by 'total' T cell transfer was restricted to extra follicular areas (Fig. 4b). Clearly, as previously described, some degree of B cell activation is inherent in adoptive T cell transfer experiments using nude mice. However, the immunisation independent formation of germinal centres and IgGl switching within them that can be observed upon depletion of CD25^+ve T cells (Fig. 4c) suggests a role for these cells in regulating the humoral response. The role of regulatory T cells in preventing polyclonal B cell hyper-activation that is described here may explain auto-antibody generation after depletion of CD25^+veT cells (Sakaguchi et al, J. hnmunol 155, 1151-64 (1995)). Example 7

Since our studies implicated CCL4 as the most effective chemo-attractant for regulatory T cells, which can clearly effect the humoral immune response, the role of CCL4 in vivo was studied. The chemokine was temporarily depleted by injection of an anti-serum, which neutralises the biological activity of CCL4 in migration assays using primary T cells (Fig.3f). It was not possible to detect any change in the spleen of any of the analysed nu-/nu- mice after injection of anti-CCL4 serum (Fig. 4d). However, if the mice were reconstituted with 'total' T cells prior to anti-CCL4serum injection, a dramatic effect on the kinetics of the humoral response and the architecture of the spleen was observed (Fig. 4e). The same effect was observed in Balb/c mice treated with the neutralising anti-serum. By day 7 nearly all follicles developed large germinal centres (Fig. 4f). This is in marked contrast to a normal immunisation (Fig. 4g), in which a minority of follicles contain nascent germinal centres. The presence of isotype switched cells in the germinal centres reflects their mature nature (Fig. 4f,h). The majority of GCs in the anti-CCL4 treated mice contained IgGl switched cells usually located distally in relation to the Thy 1.2+ T cell area (Fig. 4h). This stain also revealed that the cells in the abundantly developed PALS associated foci also expressed IgGl (Fig. 4f). This increase in IgGl expressing cells results in elevated serum IgGl levels (Fig. 6a). The anti-CCL4 induced reorganisation appeared to be independent of additional antigenic stimulation. Purified goat immunoglobulin does not accelerate germinal centre formation, suggesting that while it may contribute as an antigenic stimulus, it is insufficient to cause the phenotype we observed.

Example 8

It was shown that activated B cells can attract regulatory T cells and that neutralisation of the dominant chemokine mediating this effect results in a grossly deregulated humoral immune response. This posed the question whether the effect we observed in our in vivo experiments is due to an effect of the regulatory T cell on T cell help or directly on B cells. To address this, it was inquired whether regulatory T cells can directly modulate LPS activated B cells. T cells were labelled with anti-CD4 PE and anti-CD25 FITC (Pharmingen) and sorted by FACS. Combinations of cells were incubated for 60-84h in RPMI (10% FCS): 5xl0⁵ B cells, 4xl0⁵ FACsorted CD25⁺ or CD25^" CD4+ cells, 2x10⁵ splenic 'input' T cells and cells migrated to CCL4. Wells were pre-coated with 2μg/ml anti-CD3e (Pharmingen) and LPS was used at 25μg/ml. Cells were counted by FACS using beads for normalisation. Two independent sources of regulatory T cells, FACS sorted small CD4^+ve CD25^+Ve cells and T cells that had actually migrated to CCL4 in vitro. Both, in vitro CD3 cross-linked T cells and 'total' input T cells compounded the LPS stimulation (Fig. 5a, b, c, e, f), presumably by providing T cell help. In contrast to this, we found that regulatory T cells completely inhibited activation induced blasting and proliferation of the B, whether derived by FACS sorting (Fig. 5f) or migration towards CCL4 (Fig. 5d and e).

Activation of B cells (and other APCs) leads to the production of a chemokine that recruits regulatory T cells, which can directly inhibit B cell activation. Interuption of this pathway by either the removal of the regulatory cells themselves or the chemokine that recruits them leads to the generation of auto-antibodies. Plates were coated with either 50μl of 5 μg/ml linear dsDNA in TE pH7.4 following pre-treatment with 5 μg/ml Poly-L-Lysine in water, or lOOμg/ml cardiolipin in absolute ethanol, or 250ng/ml myeloperoxidase in bicarbonate buffer pH9.3. For IgGl level measurement, plates were incubated overnight at 4°C with 8 μg/ml of IgGl capture antibody (Pharmingen) in sterile 0.1M NaHCO₃. Plates were blocked with 10% FCS in PBS. 3 fold sera dilution steps were incubated, washed and bound antibody was detected using 2μg/ml biotinylated anti-mouse IgG, followed by 0.5μg/ml Sfreptavidm-HRP or Avidin-AP (myeloperoxidase plates). Colorimetric detection was by ABTS or pNPP. Indeed, we were able to detect IgG auto-antibodies to 3 different self antigens only seven days after anti-CCL4 treatment (Fig.6b, c, d). The concentration of these auto- antibodies in the serum appears to plateau around day 28 and remains elevated beyond 60 days (data not shown). Antibodies to dsDNA, myeoloperoxidase and cardiolipin were not detectable in control mice. Example 9

The inventors have shown that upon activation B cells and professional APC up-regulate CCLl and/or CCL2 and/or CCL3 and/or CCL4. Amongst these, CCL4 is the most efficient chemo-attractant for regulatory T cells in vitro. It is possible that in vivo synergistic or additive effects amongst these chemokines may come into play. However, the profound effect of CCL4 depletion suggests that this chemokine plays a central role in vivo. Regulatory T cells have been implicated in modulating T cell function and results show regulatory T cell recruitment occurs at the level of APC activation. Furthermore, these cells are not only recruited efficiently by B cells, but directly affect the humoral response. While regulatory T cells can clearly influence T helper cells our findings suggest an additional more direct effect on B cells. Indeed, our data indicates that regulatory T cells can affect B cell function in vitro in the absence of helper T cells (Fig. 5). The functional interaction between regulatory T cells and APC is further supported by a number of gene deletion models involving genes implicated in this network. Whilst having diverse phenotypes resulting from pleiotropic effects, all lead to exaggerated lympho-proliferation and in many cases to auto-immunity. These include CD25, CTLA-4 and TGFβ all of which are markers for regulatory T cells.

Example 10

CCL4 preferentially attracts CCR5 ^■+ cells

Upon activation, B cells and professional antigen presenting cells up-regulate the expression of the chemokine CCL4. This chemokine has been shown to be a potent chemo-attractant for CD4⁺CD25⁺ regulatory T cells (Bystry et al). The chemokine receptor responsible for mediating CCL4 induced migrations remains unknown. However, binding studies have shown that the receptor CCR5 (Meyer A. et al. J Biol Chem 1996; 271: 14445-51) can bind CCL4, which make it a likely candidate. As a first step in analysing the potential role of CCR5 in the recruitment of regulatory T cells we examined whether the cells migrating towards CCL4 indeed express this receptor. We used splenic lymphocytes as input cells in transwell migration assays with a range of CCL4 concentrations (0ng/ml-500ng/ml). The cells that had migrated in transwell migration assays (3 independent assays for each concentration of chemokine, 2 wells per assay) within 3h were then immuno-stained with a combination of CCR5 and either CD4, CD8 or CD 19 (Fig.8) and analysed by FACS using beads for quantification.

Cells of all three cell-types were represented amongst the cells that had migrated towards CCL4 (Fig.δa, e, i). The uniting feature of these cells was the fact that the majority of them expressed CCR5. The number of cells that had migrated was rather low. However, this has to be seen in the light that CCR5 positive cells are very rare in total splenocyte preparations. Only 1.8% of the CD4⁺ cells (Fig.8b), 1.6% of the CD8⁺ cells (Fig.8f) and 3.3% of the CD19⁺ cells (Fig.8j) cells in the input population expressed CCR5. In contrast to this 61.8%) of the CD4⁺ cells (Fig.8c), 49.4% of the CD8⁺ cells (Fig.8g) and 82% of the CD19⁺ cells (Fig.8k) that had actually migrated towards CCL4 were CCR5 . To correctly assess the potency and specificity of the migration to CCL4, the low number of CCR5⁺ cells in the input cell population has to be taken into account. The potency of the migration is proportional to the total number of migrated cells (Tm), while the specificity is proportional to the number of migrated cells expressing the marker of concern - in our case CCR5 - (Cm) and inversely proportional to the number of input cells expressing the marker (Ct). Hence the migration index (Tm*Cm Ct) is a more accurate indicator of migration potency and specificity.

CD4⁺CCR5⁺ cells exhibited migration index of 63.5 in migrations to 500μg/ml of CCL4 while the index for CD4⁺CCR5^" were significantly lower (Fig.8d). The same is true for CD8⁺CCR5⁺ (Fig.8h) and CD19⁺CCR5⁺. (Fig.81). It thus appears that CCR5⁺ cells preferentially migrate towards CCL4. Clearly, CCR5 is a good marker for cells that will migrate towards CCL4, however, whether it is the one and only receptor that can recruit these cells will have to be analysed using cells from CCR5 gene deletion mutants. Example 11

CCR5 marks a subset of CD4⁺CD25⁺ and CD8⁺CD25⁺ T cells.

Recently, expression of the IL2 receptor alpha subunit (CD25) on CD4⁺ cells has become the gold standard for the identification of regulatory cells, despite the fact that it is also expressed on activated T cells and anergic T cells. Therefore, we were keen to investigate the relationship between CCR5 and CD25 expression on T cells in the hope that it distinguishes the various CD25⁺ cell populations.

We performed a detailed FACS analysis of CD25 and CCR5 on CD4⁺ and CD8⁺ lymphocytes prepared from the spleen (Fig.9), blood and lymph nodes (data not shown). CCR5 was expressed on about 21.4% of CD4⁺CD25⁺ cells (Fig. 9a). In contrast to this most, if not all of CD4⁺CCR5⁺ cells were CD25⁺ (Fig. 9b). Similarly, 23.1% of CD8⁺CD25⁺ cells expressed CCR5 (Fig.9c) and 91.5% of CD8⁺CCR5⁺ expressed CD25 (Fig.9d). To ascertain that we are indeed dealing with T cells and not rare CD4⁺ or CD8⁺ subpopulation of dendritic cells we checked CCR5⁺ cells for the expression of CD3 and found the majority of CCR5⁺ cells to express to express this T cell marker (Fig.9e and f).

Example 12

CD4⁺CCR5⁺ are potent regulatory cells

CCR5 is expressed on those 20% of CD4+CD25+ cells that are preferentially recruited by CCL4. This is particularly interesting since interference with the CCL4 mediated recruitment or retention of cells has been shown to lead to a deregulation of immune system and the formation of auto-antibodies (Bystry et al.).

We therefore examined the regulatory potential of CD4⁺CCR5⁺ cells in controlling the proliferation and blasting of target CD4⁺, CD8⁺ or CD19⁺ cells. To this end we performed in vitro proliferation assays, by co-culturing CD4⁺CCR5⁺ cells with purified target cell populations for 3 days.

Standard ³H-Thymidine incorporation assays are not ideally suited to address this kind of question, as neither target nor putative suppressor populations can be irradiated. The extent of the contribution of the various cell populations to the 'blindly' measured ³H- Thymidine incorporation remains unclear. For example, wells containing targets CD19⁺ cell and CD4⁺CD25^" negative cells would show higher incorporation due to the growth of the CD4⁺CD25^" cells added, while wells containing targets and CD4⁺CD25⁺ would show lower incorporation due to the anergic nature of the regulatory population. Even without any regulatory component these experiments would still exhibit marked differences. Therefore we opted for an alternative and in our opinion far more accurate assay. To ensure that the effects on the target cell proliferation were purely a result of active suppression by the regulatory population we labelled the target cells with CFSE. After 3 days of culture we measured the proliferation of the CFSE-labelled target cells by FACS. Using beads for normalisation we were able to quantify the proliferation of the target, helper or suppressor cells independently. Furthermore, analysing replica wells immediately after plating allowed us to ensure the exact cell composition of each experimental set. All experiments were done with freshly isolated cells. For each data set at least three completely independent experiments were performed.

The first question we addressed was whether CD4⁺CCR5⁺ cells have a regulatory effect on other CD4⁺ cells. We incubated 2x10⁴ target CD4⁺CCR5^" cells with CD4⁺CCR5 cells at a 10:1 ratio (Fig.lOa to d). The input cells showed a reduction in forward scatter after 3 days of culture (Fig. 10a), indicating that the cells are starting to die. In contrast to this, the target cells blast in the presence of anti CD3 stimulation (Fig. 10b). The addition of CD4⁺CCR5⁺ cells significantly reduced the anti-CD3 induced blasting (Fig. 10c) and proliferation (Fig. lOd) of the target cells. Notably and in contrast to the un-stimulated target cells, the cells suppressed by the CD4⁺CCR5⁺ cells didn't show any change in scatter profile indicating their demise nor could we measure any significant uptake of propidium iodide (data not shown). As activated B cells, like all professional antigen presenting cells, express CCL4 (Bystry et al), we would expect CD4⁺CCR5⁺ cells to be recruited by them. We have already demonstrated that regulatory T cells can directly inhibit proliferation of B cells. Thus it didn't surprise us to find that addition CD4⁺CCR5⁺ to activated B cells resulted in very effective suppression of the anti IgM-induced proliferation (Fig lOe to i)

Similarly, CD4⁺CD25⁺ regulatory cells have been reported to have an effect on the proliferation of CD8⁺ cells (Piccirillo C.A., et al, J. Immunol., 2001,167:1137-1140). Our experiments show that CD4⁺CCR5⁺ have a pronounced inhibitory effect on the proliferation of anti-CD3 activated CD8⁺ cells (Fig.101 to n), yet not unlike the suppressed B cells, the CD8+ cells nevertheless appeared to blast despite the presence of CD4⁺CCR5⁺(Fig. 10m,n).

In summary, it can be said, that CD4 CCR5 cells have all the inhibitory effects on CD4⁺, CD19⁺ and CD8⁺ cells, previously ascribed to CD4⁺CD25⁺ regulatory T cells. It is notable that we in general perform our assays with a 10:1 ratio (or less) of target cell to CD4⁺CCR5⁺ cell, which is substantially lower than the ratios used by many groups. This indicates to us that either we are dealing with a more potent inhibitor or with a purer population of regulatory cells. As only about 20%) of CD25+ cells are CCR5+ (Fig.9a) it wouldn't be too surprising to find the same regulatory effect at a 5 fold reduced ratio of cell populations. To formally address our hypothesis that CD4⁺CD25⁺CCR5⁺ cells are the subpopulation of CD4⁺CD25⁺ cells that carries the main regulatory function we compared the regulatory effect of CD4⁺CCR5⁺ (which by definition are also CD25⁺) with that of CD4⁺CD25⁺CCR5^" cells.

In a co-culturing experiment using CD4 cells as target, CD4⁺CCR5⁺ cells led to marked reduction of the CD4 cell proliferation at a 1:50 ratio (Fig.l3a). Using the same number of CD4⁺CD25⁺CCR5^" cells had no significant inhibitory effect. When we increased the number of CD4⁺CD25 CCR5^" cells we appeared to gradually increase the inhibitory effect (Fig.l3a), until, at an about lOfold lower ratio, we observed a similar inhibitory effect (data not shown). Whilst, we cannot exclude that CD4⁺CD25⁺CCR5^" cells also have a regulatory effect albeit less potent, we think that the observed effect might well be due to contaminating CCR5+ cells, which for technical reasons cannot be completely removed.

Example 14

CD8⁺CCR5⁺ are potent regulators of CD8⁺ cells

In the current renaissance of suppressor T cells as CD4+CD25+ regulatory cells, reports of inhibitory effects mediated by CD8+ cells have moved somewhat into the background. However, there is a substantial body of literature describing CD8⁺ cell mediated effects ranging from the induction of oral tolerance (Ke, Y. and Kapp, J.A.,

J. frnmunol., 1996, 156:916-921, Grdic D. et al, J. Immunol, 1998, 160:754-762) and prolonged allograft survival (Zhou, J., et al, J. frnmunol., 2001, 167:107-113) including both direct (Gilliet, M and Liu Y-J., J.Exp.Med., 2002, 195(6):695-704) and indirect modulation (Chang, CC. et al, Nat.hnmunol, 2002, 3(3):237-243) of immune responses. Having identified a CD8⁺CCR5⁺ cell population, which by all criteria mirrored the population of CD4⁺CCR5⁺ regulatory T cells, we were intrigued whether these cells also have inhibitory activities and analysed them in co-culturing experiments.

In analogy to the experiments described above, we used CFSE-labelled CD8⁺CCR5^" as targets to investigate effects of CD8⁺CCR5⁺ on CD8⁺ cells. Not unlike B cells without activation, the input CD8⁺CCR5^" show reduction in forward scatter after 3 days in culture (Fig.l 1 a), while they blast and proliferate if grown in the presence of anti-CD3 (Fig.llb, d). When CD8⁺CCR5⁺ cells were added at a 30:1 ratio (keeping total numbers constant) we observed a drastic reduction in both blasting (Fig.l lc) and proliferation (Fig.lld).

Since the activation of CD8⁺ is restricted by MHC class I and is unclear as to whether B cells and CD8+ cells ever come into physiological contact, one wouldn't expect any effect of CD8⁺ cells on B cells. Nevertheless, adding anti-CD3 activated CD8⁺CCR5^" cells to anti-IgM activated CD19⁺ target cells compounds their proliferation (Fig Hi), possibly due to bystander help by the secretion of cytokines (Mosmann T.R. et al., Semin Immunol, 1997, 9(2):87-92), although any physiological meaning of this remains unclear. Addition of equal numbers of CD8 cells including CD8⁺CCR5⁺ at an overall 20:1 target to suppressor cell ratio does not affect the blasting of anti-IgM activated CD19⁺ target cells (Fig.llh). Although, one can observe a slight effect on the proliferation of CD19⁺ target cells, it still remains higher than the control (Fig.l If, i). The CD8⁺CCR5⁺ cells in the co-culture are actually inhibiting the CD8⁺CCR5^" cells (data not shown), thus reducing their bystander help effect on CD19⁺ cells (Fig 12i).

Whilst there have been reports of CD8⁺ cells having indirect regulatory effects on CD4 cell mediated immune responses by exerting effects on antigen presenting cells (Chang, CC. et al, Nat mmunol, 2002, 3(3):237-243), a direct effect on CD4+ would not be expected.

Thus, it was came to no surprise that we could not observe any difference in the CD4⁺ target cell blasting or proliferation (Fig llj-n). The experiment was internally controlled as we could observe a clear effect on the proliferation of CD8⁺CCR5^" in the wells that contained CD8⁺CCR5⁺ (data not shown) yet again highlighting the strength of our approach in preventing artificial effects.

Example 15.

Comparison of the regulatory potential of CCR5+ and CD25+ CCR5- cells, effect of CCR5 depletion on the suppressive potential of CD4+CD25+ cells and regeneration of CCR5+ cells, (a) CFSE-labelled CD4+ CCR5- CD25- target cells were activated with anti-CD3 antibody and co-cultured for 3 days with 2% CD4+ CCR5+ or various amounts (2%-8%) of CD4+ CCR5- CD25+ cells. The proliferation of the CFSE labelled target cells was analysed by FACS on day 3. (b) CFSE-labelled CD4+ CCR5- CD25- target cells were activated with anti-CD3 antibody and co- cultured for 3 days with CD4+ CD25+ or CCR5-depleted CD4+ CD25+ cells. The proliferation of the CFSE labelled target cells was analysed by FACS on day 3. (c) In vitro regeneration of CCR5+ cells: (live) total lymphocytes were stained for CCR5, depleted by autoMACS of CCR5+ cells, and re-stained for CCR5. (dead) The experiment was repeated with cells pre-fixed with paraformaldehyde. (d) In vivo regeneration of CCR5+ cells: (input) CFSE-labelled (control) total or (depleted) CCR5-depleted lymphocytes from spleens of Balb/c mice were stained for CCR5 and injected i.v. into matched nu-/nu- mice, (in vivo) After 3 days the splenocytes of the nu-/nu- mice that had received (control) total lymphocytes, (depleted) CCR5-depleted lymphocytes or (not shown) no injection were harvested and the CFSE+ cells were stained for CD4 and CCR5. These results suggest that potent CCR5+CD25+ regulatory T cells are generated from precursor CCR5- CD25+ T cells.

The results are shown in Figure 13.

Example 16. Up-regulation of CCR5 expression upon activation of CD25⁺ or CD25" cells., (a-f) FACS analysis and proliferation assays after in vitro culture of (a- c) CD4+ cells and (d-f) CD8+ cells, (a) CD4+CD25+ or (b) CD4+CD25" were depleted of CCR5 and cultured either without activation, or in the presence of IL2 or IL12 plus anti-CD3 and anti-CD28. After 3 days the cells were harvested, adding the same amount of CaliBRITE beads in all wells for quantification of proliferation, and stained for CD25 and CCR5. This allowed accurate assessment of the relative number of (grey bars) CD25+CCR5" cells versus (black bars) CD25+CCR5+ cells present.

(c) Suppression assay using CFSE-labelled CD4⁺ cells as targets. CCR5-depleted

CD4+CD25+ cells or CCR5-depleted CD4+CD25" that were cultured for 1 day in the presence of IL12, antiCD3 and antiCD28 were stained for CCR5, and sorted into CCR5 ⁺ and CCR5" subpopulations, which were then co-cultured with CD4 ⁺ CFSE- labelled targets. Proliferation was analysed by FACS after 3 days, (d-f) FACS analysis and proliferation assays after in vitro culture of CD8⁺ cells, (d) CD8⁺CD25⁺ or (e)

CD8⁺CD25- were depleted of CCR5 and cultured either without activation, or in the presence of IL2 or IL12 plus anti-CD3 and anti-CD28. After 3 days the cells were analysed as described in (a, b) for relative number of (grey bars) CD25+CCR5" cells versus (black bars) CD25⁺CCR5⁺ cells present, (n.d.) not determined due limitations of the available cell numbers, (f) Suppression assay using CFSE-labelled CD8⁺ cells as targets. CCR5-depleted CD8⁺CD25" that were cultured for 1 day in the presence of

IL4, antiCD3 and antiCD28 were stained for CCR5, and sorted into CCR5+ and CCR5" subpopulations, which were then co-cultured with CD8⁺ CFSE-labelled targets. Proliferation was analysed by FACS after 3 days. IL4 was chosen for the

CD8⁺CD25" activation as it was marginally more potent than IL12 in inducing CCR5 up-regulation by day 1. (g, h) Quantitative RT-PCR of Foxp3 expression levels normalised to hprt expression and to total CD4⁺ cells: (g) ex vivo isolated CD4⁺, CD8+ cells and corresponding CD25-CCR5", CD25+CCR5" and CD25⁺CCR5⁺ subpopulations. (h) in vitro activated cells: CCR5-depleted CD4⁺CD25⁺ or

CD4+CD25" cells were activated for 2 days with antiCD3, antiCD28 and IL2 or IL12 respectively and then sorted into CCR5⁺ and CCR5" subpopulations, from which RNA was extracted for the RT-PCR analysis shown. These results suggest that pro- inflammatory helper T cells can also express CD25 and CCR5 after in vitro activation. However these are not the same cells as the CCR5+ CD25+ regulatory T cells, which are (i) potently suppressive, (ii) express the gene FoxpS (in ihe case of CD4+ suppressors) and (Hi) express CCR5 and CD25 prior to any activation.

The results are shown in fig 14.

Example 17. Activation of CD4+CD25+ Treg cells in the presence of co- stimulation via CD40L leads to CCR5 up-regulation and enhanced suppressive potency. (a) Percentage of freshly isolated splenic CD4+CD25+ cells expressing CCR5 after 48h incubation in the presence of no activation or anti-CD3, anti-CD 154(CD40L) and 5ng/ml IL2. (b) Freshly isolated CD4+CD25- cells were used as targets in a proliferation assay. Proliferation is normalised to the proliferation of target cells alone (control). CD4+CD25+ or CD4+CD25- cells were added after 48h pre-incubation on anti-CD3 coated plates in the presence or absence of anti-CD154 and 5ng/ml IL2. These results suggest that the suppressive potency and the expression of CCR5 (and thus the ability to be recruited via CCL4) of CD25+ regulatory T cells can be enhanced by stimulating the regulatory cells with anti-CD3 and/or anti-CDl 54 and/or IL-2.

The results are shown in fig 15.

Example 18. Proposed CD4 and CD8 T cell lineage based on the expression of CD25 and CCR5. There are two populations of CD25 cells in the CD4 T cell lineage. One of them marks regulatory T cells, is thymically selected and thought to be self-renewing upon stimulation in the presence of IL-2. The other represents activated helper T cells. Both CD25+ populations have CCR5+ subpopulations, which form out of the pool of CD25+ CCR5- cells. The two CD25+ populations are non-overlapping and have diametrically opposed functions. In both cases, the CCR5+ cells appear to be the 'effector' arm of the populations. The transcription factor Foxp3 is only expressed in regulatory T cells and can be used to distinguish the two populations. An analogous scenario can be observed for the CD8 T cell lineage. However, the relationship between the two CD25+ populations is not yet understood. As Foxp3 is not expressed in CD8+ cells, it cannot be used to distinguish between the regulatory and the cytotoxic population.

The results are shown in fig 16.

Example 19. Relative expression of CCL4 mRNA in uterine tissue of pregnant versus non-pregnant mice. Uterine tissue from a mouse in diestrous (identified by vaginal smear and Giemsa staining) or a syngeneically mated pregnant mouse at day E12.5 of gestation were analysed by quantitative real-time PCR for the expression of CCL4 mRNA. These results suggest that CCL4, which can recruit CCR5+ regulatory T cells, is expressed in the uterus of pregnant females. This may enable the recruitment of CCR5+ regulatory T cells to the pregnant uterus, thereby blocking the mothers ' immune system from attacking the (semi-allogeneic) fetus. Hence immunological rejection of the fetus and pre-eclampsia are avoided.

The results are shown in fig 17.

Example 20. Effect of progesterone on ex vivo cultured uterine tissue from a non- pregnant mouse. Uterine tissue from a non-pregnant mouse was incubated in the presence or absence of lOnM progesterone. After 4 hours RNA was isolated from the tissues and analysed by quantitative real-time PCR for the expression of CCL4 mRNA. These results suggest that progesterone, which is upregulated during pregnancy, can lead to CCL4 expression by uterine tissue. This may enable the recruitment of regulatory T cells (via CCR5-CCL4 interaction) to the pregnant uterus, thereby averting the mothers ' immune system from attacking the (semi-allogeneic) fetus. Hence immunological rejection of the fetus and pre-eclampsia are avoided.

The results are shown in fig 18.

Example 21. FACS analysis of CD8+ and CD4+ lymphocytes isolated from the uterus of a pregnant mouse. The lymphocytes were analysed for the expression of CCR5 and CD25. The results suggest that the vast majority of CD4+CD25+ and CD8+CD25+ cells in the pregnant uterus are CCR5+. These results suggest that the regulatory T cells present in the pregnant uterus are all potenly suppressive CCR5+ regulatory T cells. Further, they suggest that these cells may be recruited to the uterus via CCL4, which is expressed by uterine tissue (i)during pregnancy or (ii) after exposure to progesterone.

The results are shown in fig 19.

Claims

1. A method for selecting one or more regulatory T-cells comprising the steps of:

(a) Providing a population of cells comprising CD25+ T-cells; (b) Assaying the cell population for the presence of cells which express CCR5; and (c) Selecting those T-cells which express CCR5 on their cell surface.

2. A method for identifying whether one or more T-cell/s are regulatory T-cell/s comprising the steps of: (a) assaying the cell for the presence of CD25+CCR5+ on the T-cell surface; and

(b) identifying a T-cell as a regulatory T cell if those one or more cells express CCR5 on that surface.

3. A method according to claim 1 or claim 2 wherein the method is performed on unactivated cells.

4. A method according to any preceding claim wherein step (b) comprises the additional feature that the cell population is assayed for the presence of Foxp3 and CD4+ in addition to CCR5.

5. One or more isolated regulatory T-cells obtained by a method according to any preceding claim.

6. One or more isolated regulatory T-cells which are CD25+, CD4+, CCR5+, Foxp3+.

7. One or more isolated regulatory T-cells which are CD25+, CD8+, CCR5+.

8. A method for modulating the immune response in a vertebrate comprising the step of increasing or decreasing, or otherwise altering, the functional activity of at least one chemokine secreted by antigen presenting cells (APCs) on their activation, and which is capable of acting as a chemoattractant for the recruitment of regulatory T-cells to APCs, wherein those regulatory T cells comprise CCR5 as a cell surface component.

9. A method according to claim 8 wherein at least one chemokine secreted by APCs on their activation binds to the CCR5 receptor.

10. A method according to claim 9 wherein at least one chemokine secreted by APCs on their activation and which binds to the CCR5 receptor is CCL4.

11. A method for modulating an immune response in a vertebrate comprising the steps of:

(a) Testing one or more chemokines for their ability to be secreted by APCs on their activation, and also which are capable of acting as chemoattractant/s for the recruitment of regulatory T-cells to APCs, wherein those regulatory T cells comprise CCR5 as a cell surface component.

(b) Selecting the one or more chemokines which possess the characteristics defined in step (a)

(c)Modulating the functional activity of the one or more chemokines selected according to step (b) in the vertebrate.

12. A method according to any of claims 8 to claim 11 wherein the functional activity of one or more chemokines is modulated using any one or more of the methods selected from the group consisting of: administering a pharmaceutically effective amount of those one or more chemokine/s to the vertebrate; administering a pharmaceutically effective amount of one or more inhibitor/s of those one or more chemokines to the vertebrate; modulating the transcription of those one or more chemokines in the vertebrate; modulating the translation of those one or more chemokines in the vertebrate; modulating the post-translational modification of those one or more chemokines in a vertebrate and modulating the intracellular or extracellular distribution of those one or more chemokines in the vertebrate.

13. A method according to claim 12 wherein the functional activity of one or more chemokines is modulated by administering a pharmaceutically effective amount of one or more inhibitor/s of those one or more chemokines to the vertebrate.

14. A method according to claim 14 wherein the one or more chemokine inhibitor/s are selected from the group consisting of: chemical chemokine inhibitors, anti-chemokine antibodies and dominant negative mutants of those one or more chemokines.

15. A method according to any preceding claim wherein the chemokine is any one or more selected from the group consisting of: CCLl, CCL4, CCL3, CCL2 and XCLl.

16. A method according to claim 15 wherein the chemokine is CCL4 and/or CCLl.

17. A method according to claim 16 wherein the chemokine is CCL4.

18. A method according to any of claims 8 to 17 wherein the chemokine is secreted from one or more APCs from the group consisting of: B-cells, dendritic cells and macrophages.

19. A method for modulating an immune response in a vertebrate comprising the step of increasing or decreasing, or otherwise altering, the functional activity of the CCR5 receptor on those regulatory T-cells comprising said receptor .

20. A method according to claim 19 wherein the functional activity the CCR5 receptor is modulated using any one or more of the methods selected from the group consisting of: administering a pharmaceutically effective amount of CCR5 to the vertebrate; administering a pharmaceutically effective amount of one or more inhibitor/s of CCR5 to the vertebrate; modulating the transcription of CCR5 in the vertebrate; modulating the translation of CCR5 in the vertebrate; modulating the post-translational modification of CCR5 in a vertebrate and modulating the intracellular or extracellular distribution of CCR5 in the vertebrate.

21. The use of a chemokine which is secreted by antigen presenting cells (APCs) on their activation, and which is capable of acting as a chemoattractant for the recruitment of CCR5+ regulatory T-cells to APCs, in the preparation of a medicament for modulating the immune response in a vertebrate.

22. The use according to claim 21 wherein the chemokine has any one or more of the features of claims 15 to 18.

23. The use according to claim 21 or claim 22 wherein the vertebrate is a human

24. A method for selecting those isolated regulatory T-cells which are capable of modulating an immune response in an individual comprising the step of:

(a) Providing a population of T-cells;

(b) Assaying those T-cells for the presence of CCR5 on the cell surface; and (d) Selecting those T-cells which comprise CCR5 on their cell surface.

25. A method according to claim 24 wherein the method is performed on unactivated T-cells.

26. A method according to claim 24 or claim 25 wherein in step (b) those cells are in addition to CCR5 assayed for the presence of CD25+, CD4+ and Foxp3.

27. The use of one or more isolated CCR5+ regulatory T cell/s which are capable of migrating towards antigen presenting cell/s (APCs) by chemoattraction mediated by at least one chemokine secreted by APCs on their activation, in the preparation of a medicament for suppressing an immune response in a vertebrate.

28. The use according to claim 27 wherein the chemokine is CCL4.

29. The use of one or more isolated regulatory T-cells according to claim 27 or 28 wherein the T-cell is in addition positive for the selection marker CD8.

30. The use of one or more regulatory T-cells according to claim 27 or 28 wherein the T-cell is in addition positive for the selection marker CD4.

31. The use of one or more regulatory T-cells according to claim 30 wherein the T-cell is in addition positive for the transcription factor Foxp3.

32. The use of one or more regulatory T-cell s described according to any one of claims 27 to 31 which are capable of migrating towards any of the APCs selected from the group consisting of: B-cells, macrophages and dendritic cells.

33. A composition comprising at least one chemokine which is secreted by antigen presenting cells (APCs) on their activation, and which is capable of acting as a chemoattractant for the recruitment of CCR5+ regulatory T-cells to APCs, or a chemokine binding molecule and a pharmaceutically acceptable carrier, diluent or exipient.

34. A composition comprising CCR5 or a modulator of the functional activity of CCR5 and a pharmaceutically acceptable carrier, diluent or exipient.

35. A composition comprising at least one or more isolated CCR5+ regulatory T cell/s selected according to the method of any one or more of claims 1 or 24 and a pharmaceutically acceptable carrier, diluent or exipient.

36. The use of at least one chemokine, which is secreted by antigen presenting cells (APCs) on their activation, and which is capable of acting as a chemoattractant for the recruitment of CCR5+ regulatory T-cells to APCs, or a chemokine binding molecule, or a composition according to claim 35 in the preparation of a medicament for the prophylaxis and/or treatment of disease.

37. The use of isolated regulatory T-cells, selected according to the method of any one of claims 1 or 24 or a composition according to claim 35 in the preparation of a medicament for the prophylaxis and/or treatment of disease.

38. The use of CCR5 or a modulator of the functional activity of CCR5 in the preparation of a medicament for the prophylaxis or treatment of disease.

39. The use according to claim 37 wherein the regulatory T-cells further comprise on their surface CD8.

40. The use according to claim 37 of CD25+, CCR5+, CD4+, Foxp3+ isolated regulatory T-cells.

41. The use according to any of claims 37 to 40 wherein the disease is any one of the following: cancer, auto-immunity, transplant rejection, infection.

42. A method for modulating the immune response of a vertebrate comprising the step of increasing or decreasing or otherwise altering the functional activity and/or the recruitment of regulatory T-cells described in any of claims 37, 39 and 40 within that vertebrate.

43. A method for the modulation of an immune reponse within a vertebrate which comprises the steps of:

(e) Isolating CD25+ CCR5- (weakly suppressive) T-cells from a vertebrate; and

(f) Converting those cell isolated according to step (a) to potently suppressive CD25+CCR5+ regulatory T-cells by their in vitro treatment with any one or more agents selected from the group consisting of: anti-CD3; anti-CD154; and IL2. (g) Introducing those cells according to step (b) into that vertebrate.

44. A method according to claim 43 wherein step (b) above is substituted for step (bi) which comprises the step of the treatment of those isolated cells above with progesterone.

45. A method according to claim 43 or claim 44 wherein the treated cells may be further enriched for CCR5 surface expression (and thus high immune suppressive function) using in vitro cell purification techniques such as FACs sorting, MACs sorting and/or filtration columns.

46. A method according to any of claims 43 to 46 wherein those regulatory T-cells may be CD4+ and/or CD8+ regulatory T-cells.

47. A composition comprising of one or more isolated CCR5+ regulatory T-cells modulated according to any of claims 43 to 46 and a pharmaceutically acceptable carrier, diluent or exipient.

48. A method for the prophylaxis or treatment of one or more conditions selected from the following: autoimmunity, transplant rejection, spontaneous abortion, pre-eclampsia and infertility comprising the step of administering to a patient in need of such treatment a therapeutically effective amount of progesterone.

49. The use of isolated regulatory T-cells or a composition comprising described within any of claims 29 to 31 and 43 to 46 in the preparation of a medicament for the prophylaxis or treatment of one or more conditions selected from the following: autoimmunity, transplant rejection, spontaneous abortion, pre-eclampsia and infertility.

50. The use according to claim 49 wherein the medicament also comprises a therapeutically effective amount of progesterone.

51. A method for the treatment of cancer and/or infection in a vertebrate which method comprises the step of disrupting the regulatory T-cell function and or migration of regulatory T-cells described within to any of claims 29 to 31 within that vertebrate.

52. A use or a method according to any preceding claim wherein the 'one or more regulatory T-cells' is a population of T-cells.