5c8 Antigen

Abstract

This invention provides a monoclonal antibody which specifically recognizes and forms a complex with a protein located on the surface of activated T cells and thereby inhibits T cell activation of B cells. This invention also provides the monoclonal antibody 5c8 (ATCC Accession No. ______). This invention provides a human CD4 − T cell leukemia cell line designated D1.1 (ATCC Accession No. ______) capable of constitutively providing contact-dependent helper function to B cells. This invention also provides an isolated protein from the surface of activated T cells, wherein the protein is necessary for T cell activation of B cells. This invention further provides an isolated, soluble protein from the surface of activated T cells, wherein the protein is necessary for T cell activation of B cells.

1 . A monoclonal antibody capable of binding to a protein which is specifically recognized by monoclonal antibody 5c8 produced by the hybridoma having ATCC Accession No. HB 10916.  
     
     
         2 . (Canceled)  
     
     
         3 . The monoclonal antibody of  claim 1 , wherein the monoclonal antibody is selected from the group consisting of chimaeric monclonal antibodies, humanized monoclonal antibodies, and human monoclonal antibodies.  
     
     
         4 - 7 . (Canceled)  
     
     
         8 . A hybridoma cell producing the monoclonal antibody of  claim 1 .  
     
     
         9 - 11 . (Canceled)  
     
     
         12 . The monoclonal antibody of  claim 1  conjugated to a therapeutic agent.  
     
     
         13 - 15 . (Canceled)  
     
     
         16 . A pharmaceutical composition comprising the monoclonal antibody of  claim 1  and a pharmaceutically acceptable carrier.  
     
     
         17 . An isolated nucleic acid molecule encoding the light chain protein of the monoclonal antibody of  claim 1 .  
     
     
         18 . (Canceled)  
     
     
         19 . An isolated nucleic acid molecule encoding the heavy chain protein of the monoclonal antibody of  claim 1 .  
     
     
         20 - 23 . (Canceled)  
     
     
         24 . An isolated protein which is specifically recognized by monoclonal antibody 5c8 produced by the hybridoma having ATCC Accession No. HB 10916.  
     
     
         25 - 31 . (Canceled)  
     
     
         32 . An isolated nucleic acid molecule encoding a fragment of the isolated protein of  claim 24 .  
     
     
         33 - 43 . (Canceled)  
     
     
         44 . An isolated, soluble protein which is specifically recognized by monoclonal antibody 5c8 produced by the hybridoma having ATCC Accession No. HB 10916.  
     
     
         45 - 49 . (Canceled)  
     
     
         50 . A pharmaceutical composition comprising the soluble activated T cell surface protein of  claim 44  and a pharmaceutically acceptable carrier.  
     
     
         51 - 58 . (Canceled)  
     
     
         59 . A method of inhibiting the activation of B cells in an animal which comprises administering to an animal an effective amount of the pharmaceutical composition of  claim 16  or  50  to inhibit the activation of B cells.  
     
     
         60 - 64 . (Canceled)  
     
     
         65 . A method of inhibiting the immune response in animals which comprises the method of  claim 59 .  
     
     
         66 . A method of inhibiting organ rejection in animals receiving transplant organs which comprises the method of  claim 65 .  
     
     
         67 . (Canceled)  
     
     
         68 . A method of inhibiting autoimmune responses in animals suffering from an idiopathic autoimmune disease comprising the method of  claim 65 .  
     
     
         69 . The method of  claim 68 , wherein the idiopathic autoimmune disease comprises psoriasis, rheumatoid arthritis, Myasthenia gravis, systemic lupus erythematosus, Graves' disease, idiopathic thrombocytopenia purpura, hemolytic anemia or diabetes mellitus.  
     
     
         70 - 111 . (Canceled)  
     
     
         112 . A method of killing tumor cells or neoplastic cells which express a protein which is specifically recognized by monoclonal antibody 5c8 produced by the hybridoma having ATCC Accession No. HB 10916 in an animal which comprises administering to the animal an effective amount of the pharmaceutical composition of  claim 16  wherein the monoclonal antibody is conjugated to a therapeutic agent to inhibit the proliferation of the tumor cells or neoplastic cells.  
     
     
         113 - 144 . (Canceled)