Compositions and methods for modulating immune responses

Abstract

The present invention provides a newly identified B7 receptor, zB7R1 that functions as lymphocyte inhibitory receptor, which is a PD-1-like molecule and is expressed on T cells. The present invention also provides the discovery of zB7R1′s ability to bind to CD155. Methods and compositions for modulating zB7R1-mediated negative signaling and interfering with the interaction of its counter-receptor for therapeutic, diagnostic and research purposes are also provided.

What is claimed is: 
     
         1 . An agonist antibody or antibody fragment that specifically binds to a zB7R1 polypeptide comprising the amino acid sequence of residues 16-140 of SEQ ID NO: 2, wherein said antibody stimulates zB7R1-mediated signaling. 
     
     
         2 . The agonist antibody or antibody fragment of  claim 1  wherein the antibody or antibody fragment is:
 a) a human monoclonal antibody or antibody fragment thereof; or 
 b) a humanized monoclonal antibody derived from a murine a murine monoclonal antibody, or antibody fragment thereof. 
 
     
     
         3 . The agonist antibody or antibody fragment of  claim 1  wherein the antibody or antibody fragment is an antibody fragment selected from the group consisting of F(ab′) 2 , Fab′, Fab, Fv, scFv, and minimal recognition unit. 
     
     
         4 . A method for treating an autoimmune disease comprising administering an agonist antibody or antibody fragment of  claim 1  to a subject suffering from the autoimmune disease. 
     
     
         5 . The method of  claim 4 , wherein the autoimmune disease is rheumatoid arthritis. 
     
     
         6 . The method of  claim 4 , wherein the autoimmune disease is Crohn's disease or ulcerative colitis. 
     
     
         7 . A pharmaceutical formulation comprising:
 a) the agonist antibody or antibody fragment according to  claim 1 ; and   b) a pharmaceutically acceptable vehicle.