Immune response enhancement by in vivo administration of B7.21g, a solublecostimulatory protein

The identification of both class I- and class II-restricted tumor-associate d peptides recognized by T cells has led to the test of these peptides as i mmunogens in experimental immunotherapy for cancer patients. However, optim al T cell activation requires signaling both through the T cell receptor fo r antigen and through costimulatory pathways. B7.1 and B7.2 are powerful co stimulatory molecules expressed on the surface of antigen-presenting cells. Using a mouse model, we have sought to optimize costimulatory signals duri ng antipeptide responses by administering a soluble form of B7.2 at the tim e of peptide immunization. Administration of B7.2Ig fusion protein signific antly enhanced T helper cell and CTL responses. These findings suggest that soluble forms of human B7.2 protein may provide a straightforward and prac tical method of supplying optimal costimulation during clinical immunothera py. (C) 1999 Academic Press.