Novel cell surface molecules recognized by monoclonal antibodies against a cell surface molecule of lymphocytic cells that play an important role in autoimmune diseases and allergic diseases have been isolated, identified, and analyzed for their functions. The cell surface molecules are expressed specifically in thymocytes, lymphocytes activated by ConA-stimulation, and peripheral blood lymphocytes, and induce cell adhesion. Antibodies against the cell surface molecules significantly ameliorate pathological conditions of autoimmune diseases and allergic diseases.

DISCLOSURE OF THE INVENTION

Pharmaceuticals useful for treating or preventing various diseases such as the above-mentioned autoimmune diseases, allergic diseases, and inflammatory diseases can be developed if the mechanism of the activation of lymphocytes such as T cells by cell adhesion through the binding between molecules involved in the transmission of the secondary signal essential for the activation of lymphocytes such as T cells mentioned above and the mechanism of the regulation of lymphocyte function are clarified, and known or unknown molecules capable of mediating cell adhesion involved in the mechanism and of transmitting signals are identified and characterized.

An objective of the present invention is to identify novel cell surface molecules having both functions of mediating such cell adhesion and signal transmission, and to clarify its structural and biological characteristics. Another objective of the present invention is to provide pharmaceuticals useful for treating or preventing various autoimmune diseases and inflammatory diseases by using the novel molecules or antibodies against the molecules.

In order to identify such useful molecules, the present inventors focused on the fact that lymphocytes such as T cells play an important role in autoimmune diseases, and the fact that cell adhesion are essential for the signal transmission of the secondary signal (costimulatory signal) from antigen presenting cells into lymphocytes, and planned to isolate and identify cell surface molecules that are expressed specifically on lymphocytic cells and that mediate cell adhesion.

The present inventors obtained monoclonal antibodies against various cell surface molecules expressed on the surface of lymphocytic cells by immunizing animals against the lymphocytic cells, and isolated and identified desired cell surface molecules that mediate cell adhesion using the monoclonal antibodies so obtained. The methods used are described in detail below.

The present inventors first administered rat lymphocytic cell line as an antigen to mice and prepared various monoclonal antibodies. Then, the monoclonal antibodies obtained were reacted with rat lymphocytic cells used as an antigen and tested the effect of the monoclonal antibodies given to the cells. As a result, one of the monoclonal antibodies was obtained has been found to agglutinate the rat lymphocytic cells strongly (this monoclonal antibody was designated "JTT-1 antibody"). Moreover, other one of the monoclonal antibodies was found to strongly inhibit the agglutination of rat lymphocytic cells induced by the "JTT-1 antibody" (this monoclonal antibody was designated "JTT.2 antibody").

Since the agglutination of rat lymphocytic cells by "JTT-1 antibody" was not inhibited by antibodies against Intercellular adhesion molecule-1 (ICAM-1) or Lymphocyte function-associated antigen-1 (LFA-1), which are the most representative known cell adhesion molecules expressed on the cells, the present inventors thought that this agglutination was caused by cell adhesion through unknown adhesion molecules having that mediate cell adhesion.

Cell surface molecules (designated "JTT-1 antigen" and "JTT.2 antigen") recognized by each of these two monoclonal antibodies were then identified, isolated, and characterized.

First, the analysis of the expression patterns of "JTT-1 antigen" and "JTT.2 antigen" in various cells were analyzed by flow cytometry based on fluorescent antibody technique using "JTT-1 antibody" and "JTT-2 antibody." While both "JTT-1 antigen" and "JTT.2 antigen" were strongly expressed in activated lymphoblast cells (activated T lymphoblast cells, activated B lymphoblast cells, etc.) activated by stimulating thymocytes and spleen cells with Concanavalin A (ConA), a mitogen, in particular, in the activated lymphoblast cells, the expression was hardly found in spleen cells not stimulated at all (these cells are sometimes called "resting lymphocytes" herein). The expression patterns of molecules recognized by each of "JTT-1 antibody" and "JTT-2 antibody" were almost the same.

Using an affinity column prepared by binding "JTT-1 antibody" to adsorbents, molecules trapped by the "JTT-1 antibody", namely, "JTT-1 antigens" were purified from the mixture of soluble cell surface molecules prepared from the above-described rat lymphocytic cells. The molecular weights of these purified "JTT-1 antigens" were analyzed by immunoprecipitation using "JTT-1 antibody" and "JTT-2 antibody" and by SDS-PAGE. As a result, it was found that molecules immunoprecipitated by each of "JTT-1 antibody" and "JTT-2 antibody" were the same, and that each molecule was a homodimer having different sugar chains. Specifically, when N-linked sugar chains were not digested, the molecules were identified as one molecule with about 47 kD under non-reduction condition, and as two molecules with about 24 kD and about 28 kD under reduction condition; and when N-linked sugar chains were digested, the molecules were identified as one molecule with about 36 kD under non-reduction condition and as one molecule with about 20 kD under reduction condition.

The adhesion of rat thymocytes to the plate coated by the purified "JTT-1 antigen" was then analyzed. As a result, thymocytes significantly adhered to the plate (namely, to "JTT-1 antigen") only in the presence of "JTT-1 antibody" and that the adhesion was significantly inhibited in the co-presence of "JTT.2 antibody", indicating that "JTT-1 antigen" was the cell surface molecule mediating cell adhesion.

Next, the present inventors cloned genes encoding "JTT-1 antigen" from rat, human, and mouse, and analyzed their structures.

First, the cDNA encoding the full length of "rat JTT-1 antigen" was isolated from the cDNA library made from the lymphoblasts derived from ConA-stimulated rat spleen by expression cloning method utilizing panning method using "JTT-1 antibody" and a completely novel rat gene was isolated and identified by determining its nucleotide sequence by dideoxy method. The cDNA encoding the full length of "human JTT-1 antigen" was also isolated from the cDNA library made from ConA-stimulated human peripheral blood lymphoblasts by plaque hybridization with using the cDNA encoding "rat JTT-1 antigen" so obtained as a probe and a completely novel human gene was isolated and identified by determining its nucleotide sequence by dideoxy method. Similarly, the cDNA encoding the full length of "mouse JTT-1 antigen" was isolated from the cDNA library made from the lymphoblasts derived from ConA-stimulated mouse spleen and a completely novel mouse gene was isolated and identified by determining its nucleotide sequence by dideoxy method. Furthermore, the cDNA encoding the full length of alternative splicing variant of "rat JTT-1 antigen" mentioned above was isolated similarly from the cDNA library made from the rat thymoma cell line and another completely novel rat gene was isolated and identified by determining its nucleotide sequence by dideoxy method.

"JTT-1 antigen" was found to be a transmembrane protein (cell surface molecule) composed of a signal sequence, an extracellular region having the glycosylation site(s), a transmembrane region, and an intracellular region by hydropathy plot analysis of the amino acid sequence encoded by the isolated cDNA of "human JTT-1 antigen". Homology search with known molecules revealed that of "JTT-1 antigens" from rat, human, and mouse had no significant homology to any known molecules including cell adhesion molecules, indicating that they are novel cell surface molecules that mediates cell adhesion.

As the result that of motif search based on the amino acid sequence of "human JTT-1 antigen", it was found that "human JTT-1 antigen" had structural similarity with the above-mentioned "CD28", a cell surface molecule on lymphocytes such as T cells, which transmits costimulatory signal important for T cell activation through cell adhesion and with "CTLA-4", a cell surface molecule on lymphocytes such as T cells, which regulates the functions of activated lymphocytes such as activated T cells, cooperating with the signal.

The structural similarity is as follows.

1. 20 or more amino acid residues including cysteine residues are highly conserved.

2. Proline repeating sequence "Pro-Pro-Pro (PPP)" essential as the ligand binding region, is conserved in the extracellular region.

3. A sequence "Tyr-Xaa-Xaa-Met (YxxM)" (Xaa and x represents any amino acid) sequence essential as the signal transmitting region is conserved in the cytoplasmic region.

The locus of the gene encoding "mouse JTT-1 antigen" on mouse chromosome was found to be "1C3", which is the same location as that of mouse "CD28" and "CTLA-4" using fluorescence in situ hybridization (FISH) method.

Next, the effectiveness of therapy of autoimmune diseases and allergic diseases by regulating the function of "JTT-1 antigen", was examined by experiments in which "JTT-2 antibody" mentioned above was administered to model rats for experimental allergic encephalomyelitis (EAE) and glomerulus basement membrane (GBM) nephritis. It was found that the pathological states were significantly suppressed in both disease model animals, and that autoimmune diseases or allergic diseases can be treated by regulating the functions of "JTT-1 antigen".

It was also found that the monoclonal antibody against "human JTT-1 antigen" significantly proliferated human peripheral blood lymphocytes, and that the proliferation was further enhanced in the co-presence of a monoclonal antibody against CD3 constituting a TcR/CD3 complex on T cells, which receives the primary signal essential for T cell activation from antigen presenting cells, indicating that "JTT-1 antigen" was a cell surface molecule involved in signal transmission into lymphocytes.

Furthermore, the present inventors succeeded in producing a fusion polypeptide comprising of the extracellular region of "human JTT-1 antigen" and Fc region of human immunoglobulin. The fusion polypeptide is useful as pharmaceuticals for treating autoimmune diseases, allergic diseases, and inflammatory diseases by regulating the "JTT-1 antigen" and/or its ligand.

Moreover, the present inventors succeeded in preparing a transgenic mouse into which a gene encoding "JTT-1 antigen" of other animal species was introduced. The transgenic mouse is useful for analyzing detailed functions of "JTT-1 antigen" and for developing pharmaceuticals for treating autoimmune diseases, allergic diseases, and inflammatory diseases. The inventors also produced a knockout mouse in which the endogenous gene encoding "mouse JTT-1 antigen" was inactivated. This knockout mouse is also useful for the above-mentioned purpose.

The present inventions relate to polypeptides, genes, antibodies, vectors, transformants, pharmaceutical compositions, transgenic mice, knockout mice and so on, which are relevant to a novel mammalian "JTT-1 antigen" isolated and identified as mentioned above. Specifically, the present invention are as described in (1) to (36) below.

(1) A polypeptide constituting a cell surface molecule having characteristics mentioned below,

(a) said cell surface molecule is expressed in at least thymocytes and mitogen-stimulated lymphoblast cells,

(b) an antibody reactive to said cell surface molecule induces adhesion between mitogen-stimulated lymphoblast cells,

(c) an antibody reactive to said cell surface molecule induces proliferation of peripheral blood lymphocytes under the coexistence within the presence of an antibody against CD3,

(d) said cell surface molecule has a partial amino acid sequence represented by Phe-Asp-Pro-Pro-Pro-Phe (SEQ ID NO:21) in its extracellular region, and

(e) said cell surface molecule has a partial amino acid sequence represented by Tyr-Met-Phe-Met (SEQ ID NO:22) in its cytoplasmic region.

(2) The polypeptide of (1) comprising the amino acid sequence of SEQ ID NO: 2 or the amino acid sequence of SEQ ID NO: 2 in which one or more amino acids are substituted, deleted, or added.

(3) The polypeptide of (1), which is encoded by a DNA hybridizing with a DNA having the nucleotide sequence of SEQ ID NO: 1 under stringent conditions.

(4) The polypeptide of (1) comprising an amino acid sequence having 60% or more homology with an amino acid sequence of SEQ ID NO: 2.

(5) The polypeptide of any one of (1) to (4) wherein said cell surface molecule is derived from human.

(6) A gene encoding the polypeptide of any one of (1) to (5).

(7) The gene of (6) wherein said gene is a cDNA.

(8) The gene of (7) wherein said cDNA has a nucleotide sequence of SEQ ID NO: 1.

(9) The gene of (7) wherein said cDNA comprises a nucleotide sequence corresponding to nucleotide residues 26 to 625 of SEQ ID NO: 3, nucleotide residues 35 to 637 of SEQ ID NO: 4, nucleotide residues 1 to 603 of SEQ ID NO: 5, or nucleotide residues 35 to 685 of SEQ ID NO: 6.

(10 A vector comprising the gene of any one of (6) to (9).

(11) A transformant into which the vector of (10) has been introduced.

(12) A transformant distinguished identified by an international deposit accession No. FERM BP-5725.

(13) A polypeptide fragment comprising an extracellular region of the polypeptide of any one of (1) to (5).

(14) The polypeptide fragment of (13) wherein said polypeptide is a human-derived polypeptide having an amino acid sequence of SEQ ID NO: 2.

(15) A gene encoding the polypeptide fragment of (13) or (14).

(16) A homodimer molecule comprising two polypeptide fragments, wherein each of the fragments comprises an extracellular region of the polypeptide of any one of (1) to (5) and said two polypeptide fragments bridged through disulfide bonds to each other.

(17) The homodimer molecule of (16) wherein said polypeptide is a human-derived polypeptide having an amino acid sequence of SEQ ID NO: 2.

(18) A pharmaceutical composition comprising either of the polypeptide fragment of (14) or the homodimer molecule of (17), or both of them, and a pharmaceutically acceptable carrier.

(19) A fusion polypeptide comprising an extracellular region of the polypeptide of any one of (1) to (5) and a constant region of a human immunoglobulin (Ig) heavy chain or a portion of the constant region.

(20) The fusion polypeptide of (19) wherein the immunoglobulin is IgG.

(21) The fusion polypeptide of (19) wherein the portion of the constant region comprises a hinge region, C2 domain, and C3 domain of IgG.

(22) The fusion polypeptide of any one of (19) to (21) wherein said polypeptide is a human-derived polypeptide having an amino acid sequence of SEQ ID NO: 2.

(23) A homodimer molecule comprising two fusion polypeptide of any one of (19) to (22) wherein the two polypeptides bridged through disulfide bonds to each other.

(24) A homodimer molecule comprising two fusion polypeptides of (22) wherein the two polypeptides bridged through disulfide bonds to each other.

(25) A pharmaceutical composition comprising either of the fusion polypeptide of (22) or the homodimer molecule of (24), or both of them, and a pharmaceutically acceptable carrier.

(26) The pharmaceutical composition of (25) wherein said pharmaceutical composition is utilized for treating autoimmune diseases or allergic diseases, or for preventing said disease symptom.

(27) An antibody or a portion thereof reactive to the polypeptide of any one of (1) to (5), the polypeptide fragment of (13) or (14), or the cell surface molecule comprising said polypeptide.

(28) The antibody of (27) or a portion of it wherein said antibody is a monoclonal antibody.

(29) An monoclonal antibody or a portion thereof reactive to the polypeptide having an amino acid sequence of SEQ ID NO: 2, the polypeptide fragment of (14), or the human-derived cell surface molecule comprising said polypeptide.

(30) A monoclonal antibody or a portion thereof reactive to the polypeptide of any one of (1) to (5) or the cell surface molecule comprising said polypeptide, wherein the effect of said monoclonal antibody on mitogen-stimulated lymphoblast cells is substantially the same as the effect of a monoclonal antibody produced by a hybridoma identified by an international deposit accession No. FERM BP-5707 on mitogen-stimulated rat lymphoblast cells.

(31) A monoclonal antibody or a portion thereof reactive to the polypeptide of any one of (1) to (5) or the cell surface molecule comprising said polypeptide, wherein the effect of said monoclonal antibody on mitogen-stimulated lymphoblast cells is substantially the same as the effect of a monoclonal antibody produced by a hybridoma identified by an international deposit accession No. FERM BP-5708 on mitogen-stimulated rat lymphoblast cells.

(32) A pharmaceutical composition comprising the monoclonal antibody of (29) or a portion thereof and a pharmaceutically acceptable carrier.

(33) The pharmaceutical composition of (32) wherein said pharmaceutical composition is are utilized for treating autoimmune diseases or allergic diseases, or for preventing said disease symptom.

(34) A hybridoma producing the monoclonal antibody of any one of (28) to (31).

(35) A transgenic mouse in which a gene encoding the polypeptide of (1) which is a human-derived gene comprising a nucleotide sequence of SEQ ID NO: 1 or a rat-derived gene comprising a nucleotide sequence corresponding to nucleotide residues 35 to 637 of SEQ ID NO: 4, which is integrated into the mouse its endogenous gene.

(36) A knockout mouse in which its endogenous gene encoding the mouse polypeptide of claim 1 comprising the amino acid sequence encoded by the gene of SEQ ID NO: 5 is inactivated so that said mouse polypeptide is not produced.

As described above, the cell surface molecule of the present invention ("JTT-1 antigen") is involved in cell adhesion through the molecule, signal transmission into lymphocytes such as T cells, and function regulation of function of activated lymphocytes. General knowledge of lymphocytic cells, cell adhesion molecules, and the relationship between them and diseases are described below just for general understanding of these biological events but the following general knowledge is not for interpreting the present invention limitedly.

Lymphocytes are roughly classified into two kinds, T cells and B cells. After differentiation from multipotent stem cells in bone marrow to lymphoid stem cells, some of them flow into blood to reach thymus. Lymphocytes differentiated and matured in thymus, which are called T cells (Thymus-derived T cells), get into blood again, and circulate through the whole body. Matured T cells have a molecule called CD3 on their surface. The existence of CD3 molecule is an marker to determine whether the cells are matured T cells or not. CD3 is a convincing T cell marker. In addition, T cells express CD4 or CD8. T cells are classified into helper T cells (Th cells) assisting the antibody production by B lymphocytes, cytotoxic T cells (Tc cells, CTL) or killer T cells that are bound to target cells to destroy them directly, suppressor T cells that suppress the antibody production by B lymphocytes, and effector T cells that secrete effector substances such as lymphokines to cause delayed allergy.

B cells are derived from the lymphoid stem cells differentiated and matured in bone marrow. B cells are those antibody-producing precursor cells since they produce antibodies with an appropriate stimulus. B cells have immunoglobulins on their cell surface, which were produced in a cell. Such immunoglobulins function as receptors for antigens. Matured B cells have both IgM and IgD on their surface. If B cells are differentiated with antigen stimulation and signals from T cells, the production of IgM increases and their C-terminal cell membrane binding regions are changed to be secreted. With sufficient stimulation, not only the surface immunoglobulins change into IgG, IgE, and IgA, but also the immunoglobulins of each class are secreted. The immunoglobulin on the B cell surface is sometimes represented as Ig, abbreviation of surface Ig, or mIg, abbreviation of membrane Ig. All Igs on the surface of the same B cell have the same antigen binding sites.

There are lymphocytes called large granular lymphocytes (LGL) or null cells, which are neither T cells nor B cells. These cells can destroy tumor cells and virus-infected cells without pre-stimulation with antigen, which is comparative to the case of cytotoxic T cells. So, they are also called natural killer cells (NK cells).

Among the T cells mentioned above, CD4-positive T cells secrete various cytokines, newly express receptors for these cytokines, enlarge their own size, start cell dividing, and proliferate, when they react with antigen-presenting cells. Prior to these reactions at the cell level, the complex between of the antigen peptides on antigen presenting cells and MHC class II molecules binds to the corresponding T cell antigen receptor (TCR). This causes various biochemical changes in the cells, and the signal is transmitted into nuclei to start the transcription of specific DNAs and to produce respective proteins. As a result, reactions at the cell level are raised. For example, cells infected with a virus produce virus proteins and they are degraded into peptides by proteasomes in the cytoplasm. A part of the peptides enters endoplasmic reticulum through TAP, forms stable complex with MHC class I molecules just produced, and transfers to the cell surface. The peptide transferred to the cell surface is recognized specifically by CD8-positive T cells, but the T cells can not yet destroy the infected cells at this stage. These T cells reacted to with the antigen expresses IL-2 receptor (IL-2R), are differentiated into CTL cellular cytotoxicity upon IL-2 action, and destroy their target cells to kill them in the next time when they meet the same antigen peptide/MHC class I complex. Cytokines required for the differentiation into CTL are not only IL-2 but also IFN.gamma. or other cytokines, which are thought to have similar actions. Thus, lymphokines secreted by T cells are necessary for the differentiation into CTL. The lymphokines are produced as the result that CD4-positive Th1 cells (CD4-positive T cells secreting IL-2 or INF.gamma.) recognize the antigen peptides derived from the same virus with class II molecules. In some cases, without the help of CD4-positive T cells, CD8-positive T cells react with antigens and produce IL-2 and other cytokines. When CD8-positive T cells are differentiated into CTL, granules increase in the cytoplasm. These granules comprise various high molecular weight proteins, represented by perforin. Perforin resembles a membrane attack complex (MAC) composed of the fifth to ninth components of complement, and makes holes in the cell membrane of target cells. In addition, the granules comprise serine proteases, LT, and proteoglycan, etc. Moreover, if CD8-positive cells differentiated into CTL receive antigen stimulation, they also secrete lymphokines such as IFN.gamma., LT, TNF, or IL-2. Moreover, T cells show blast transformation phenomenon, when they react with hemagglutinin (phytohemagglutinin, PHA) or ConA.

Matured T cells not yet stimulated at all are called resting T cells, and have smaller cell size and shorter lifetime, a few days. When they receive stimulation, the cells enlarge as already mentioned above, and are apt to react with various kinds of stimulation. Such T cells are called activated T cells. A part of the activated T cells become memory T cells, which bring secondary immunoreaction if they receive the same antigen stimulation. Memory T cells are thought to be kept in circulating around the body for a few years or decades.

B cells not yet stimulated at all are called resting B cells like in the case of T cells, and proliferating B cells stimulated with multivalent antigens or CD40L, are called activated B cells. Since resting B cells have no costimulator molecules, which stimulate T cells with signals through TCR, such as B7-1 (CD80) or B7-2 (CD86), presenting antigens to resting T cells are thought only to stimulate TCR and to be unable to express CD40 ligands (CD40L) or produce lymphokines. Therefore, it is thought that activated helper T cells stimulated with antigen presented by other antigen-presenting cells react with the antigen presented by resting B cells. Namely, if an antigen invades, first, dendritic cells (cells having extremely dendritic projections) expressing B7 molecules or macrophages activated by reacting with microorganisms present the antigen and stimulate resting helper T cells to activate them so as to express CD40L. The activated helper T cells then bind to resting B cells presenting the same antigen and stimulate their CD40. Once B cells are activated by stimulation with multivalent antigens or CD40L, they also express B7 molecules, activate helper T cells by stimulating CD28 on their surface with TCR, and allow the helper T cells to express CD40L or produce lymphokines. B cells that show changes such as the expansion of the cell size with stimulation but not show antibody secretion are called activated B cells. If B cells so matured meet antigens, the IgM production increases together with the stimulation from T cells and the IgM molecules so produced are secreted by turning from the membrane type into secretory type. Moreover, they produce isotypic antibodies other than IgM, such as IgG upon the humoral factors from T cells. This is called isotype switching or class switching. B cells secreting antibodies are called antibody-secreting cells. A part of them becomes morphologically characteristic cells and is called a plasma cell (Knowledge of Immunology, Ohmsha, (1996)).

Incidentally, in various reactions of immune system, the subpopulation of white blood cells, namely, T lymphocytes, B lymphocytes, NK, neutrophils, etc., often show dynamics different from one another. Even the same lymphocytes as mentioned above show dynamics different from one another depending on whether the cells are activated or resting. These facts imply the existence of recognition mechanism specific to the subpopulation of white blood cells, further, recognition mechanism specific to the state of cells, and, in particular, cell adhesion molecules (cell adhesion proteins).

Cell adhesion molecules, namely, or cell adhesion proteins are, in general, the molecules that adhere cells to each other in the development and differentiation of individuals or in migration of cells to local site, and are known to be essential molecules for organic and functional contacts in a living body.

Cell adhesion molecules are roughly classified from their structural characteristics into five (5) families, immunoglobulin superfamily, integrin family, selectin family, cadherin family, and CD44 family. Adhesion molecules belonging to immunoglobulin superfamily are characterized by the existence of repeated loop-like domains formed with disulfide bonds. Examples thereof are intercellular adhesion molecule-1 "ICAM-1" and vascular cell adhesion molecule-1 "VCAM-1." In addition, adhesion molecules belonging to integrin family are characterized by .alpha./.beta. heterodimer structure. Examples thereof are "VLA-1 to 6" lymphocyte function-associated antigen-1 "LFA-1", "Mac-1," and "p150/90." Molecules belonging to selectin family have lectin-like domain, EGF-like domain, and complement domain in this order from N terminus. Examples thereof are "E-selectin" and "P-selectin." Examples of cadherin family are "E-cadherin," "N-cadherin," and "P-cadherin," and an example of CD44 family is "CD44".

The specific function of these adhesion molecules is known to be adhesion of white blood cells to vascular endothelial cells or of lymphocytes to antigen-presenting cells. From recent various studies, it has been gradually revealed that adhesion molecules are involved not only in these functions but also in various diseases.

In particular, there are many reports on diseases and expression abnormality of adhesion molecules. For example, as for rheumatoid arthritis (RA), the expression of both "Mac-1" and "p150/95" was reportedly strengthened in RA synoviocytes (Allen et al., Arthritis Rheum., 32:947, 1989). It has also been reported that various cells expressed "ICAM-1" strongly and ectopically on RA synovial membrane (Hale et al., Arthritis Rheum., 32:22, 1989). Another report implied that "ELAM-1" was also involved in the adhesion of neutrophils to vascular endothelial cells and that the overexpression of these molecules was involved in infiltration of neutrophils (especially, into synovial fluid), which is observed in RA synovial fluid (Laffon et al., Arthritis Rheum., 32:386, 1989). Strong expression of "CD44" in vascular endothelial cells and A-type synoviocytes on RA synovial membrane was reported (Heynes et al., Arthritis Rheum., 34:1434, 1991).

There are reports on the relationship between systemic lupus erythematosus (SLE) and the expression abnormality of adhesion molecules. For example, adhesion ability of T lymphocytes to cultured vascular endothelial cells was reportedly lowered in SLE patients, compared to healthy volunteers. In peripheral lymphocytes of SLE patients, adhesion molecules "ICAM-1", "VLA-4", and "IFA-1" to were strongly expressed (Haskard et al., Rheumatol. Int., 9:33, 1989).

In autoimmune thyroiditis diseases, it was reported that "ICAM-1" was expressed when a thyroid follicular cells were stimulated with interferon-.gamma., interleukin-1, and tumor necrosis factor, and that the formation of cluster of follicular cells and mononuclear cells was inhibited by anti-"ICAM-1" antibody (Weetman et al., Eur. J. Immunol., 20:271, 1990).

In hepatitis, it is thought that the chances of adhesion between hepatocytes and inflammatory cells increases since there are two pathways of adhesion, "ICAM-1" and "LFA-3", and "LFA-1" and "CD2", to thereby promote presentation of antigens and activation of inflammatory cells. In particular, in hepatitis B, "LFA-3" molecules are strongly expressed in hepatocytes, in which viruses are actively proliferating, and "ICAM-1" well correlates with the degree of hepatitis. It is thus implied that "LFA-3" is involved in the exclusion of viruses and "ICAM-1" promotes T cells to present antigen and regulates inflammation reaction. In "ICAM-1"-negative and HBc antigen-positive hepatocytes, chronic virus infection, a kind of immunounresponsiveness, may occur due to no interaction between lymphocytes and hepatocytes. It has also been reported that serum "ICAM-1" in chronic liver disease may correlate with the degree of hepatocyte damage because the serum "ICAM-1" concentrations in acute hepatitis patients, chronic active hepatitis patients, and liver cirrhosis patients were higher than that in healthy volunteers and chronic persisting hepatitis patients, and the concentration was high in the case of histologically progressing active hepatitis (Mod. Phys., 15:73 76, 1995).

In a model animal of arteriosclerosis, adhesion and invasion of monocytes and lymphocytes to vascular endothelium were observed at very early stages of the onset of the disease. It is thus thought that the interaction of these hemocytes with endothelium is the first step of the onset of arteriosclerosis. Various reports show the expression of adhesion molecules in actual arteriosclerosis nidus including the expression of "ICAM-1" in human arteriosclerosis nidus (Poston et al., Am. J. Pathol., 140:665, 1992) and the expression of "VCAM-1" in arteriosclerosis nidus of a hypercholesterolemia rabbit (Cybulsky et al., Science, 251:788, 1991). A recent report revealed that the expression of "VCAM-1" was observed in human arteriosclerosis nidus, and, in particular, strong expression in smooth muscle cells migrating to intima and in monocytes/macrophages. In addition, since the expression of "MCP-1" was enhanced in rabbit and human arteriosclerosis nidus, suggesting that "MCP-1" promotes the formation of arteriosclerosis nidus through the migration of monocytes/macrophages (Current Therapy 12:1485 1488, 1994).

The relationship between tumor metastasis and adhesion molecule abnormality has also been reported. For example, if E-cadherin-decreased cancer cells showed strong invasiveness, but the invasiveness was inhibited by introducing the cDNA of E-cadherin into the cancer cells, the invasiveness was recovered when E-cadherin antibodies antiserum was added to the cells. This suggests the tight relationship between the decrease in the expression of E-cadherin and invasiveness of tumor cells (Frixen et al., 113:173, 1991). In actual clinical cases, the relationship between the decrease of the expression of E-cadherin and metastasis is pointed out in various kinds of cancer such as hepatoma, esophageal cancer, gastric cancer, and breast cancer. It has also been reported that "VLA-4" molecules, a ligand for "VCAM-1", were highly expressed in metastatic melanoma, gastric cancer, and breast cancer, suggesting that this molecule can could be utilized for the implantation to vascular endothelial cells in metastasis. In addition, based on experiments using various tumor cell lines, it has been reported that epithelial cancer, such as gastric cancer, colon large intestine cancer, lung cancer, hepatoma, or pancreatic cancer, adhered to vascular endothelial cells through E-selectin (Takada et al., Cancer Res., 53:354, 1993).

On the other hand, therapeutic approach to treat diseases by targeting these adhesion molecules have been made. For example, it was reported that anti-rat "ICAM-1" antibody strongly inhibited inflammatory reaction in rat autoimmune arthritis model. It has also been reported that the administration of anti-"ICAM-1" antibody inhibited the onset of arthritis in adjuvant synovitis in one of animal models of RA (Nihon et al., 14:571 577, 1991). It was further reported that the metastasis formation of inoculated tumor was remarkably inhibited if a large amount of peptides having REG sequence, which is that an amino acid sequence in an extracellular matrix protein recognized and bound by some integrins, were administered to a gallbladder cancer mouse, and that in in vitro system RGD peptides and anti-.beta.1 subunit antibody inhibited the motion and infiltration of tumor cells (Yamada et al., Cancer Res., 50:4485, 1990).
 

Claim 1 of 119 Claims

1. A purified antibody that binds to a polypeptide consisting of SEQ ID NO:2, wherein the antibody is a human, mouse, rat, guinea pig, rabbit, dog, cat, pig, goat, horse or cow antibody.

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