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.

1 . A monoclonal antibody or antibody fragment that specifically binds to the extracellular domain of zB7R1 (SEQ ID NO:3), wherein said antibody or antibody fragment blocks or inhibits the interaction of zB7R1 with CD155. 
     
     
         2 . The antibody of  claim 1 , wherein the antibody is selected from the group consisting of a murine monoclonal antibody, a humanized antibody derived from a murine monoclonal antibody, and a human monoclonal antibody. 
     
     
         3 . The antibody fragment according to  claim 1 , wherein the antibody fragment is selected from the group consisting of F(ab′) 2 , Fab′, Fab, Fv, and scFv. 
     
     
         4 . A composition comprising:
 an antibody or antibody fragment according to  claim 1 ; and   a pharmaceutically acceptable vehicle.