anti-CD278 (human), Rabbit Monoclonal (RM417)

CD278 (ICOS; CRP1; CD28-related protein-1) is a member of the growing CD28 family of immune costimulatory receptors. Other family members are CD28, CTLA-4 and PD-1. ICOS is expressed on most CD45RO+ cells. ICOS expression is upregulated within approximately 24-48 hours of activation on Th primed cells. B7-H2, a member of the B7 family of costimulatory ligands, has been identified as the ICOS ligand. The B7-H2/ICOS interaction appears to play roles in T cell dependent B cell activation and Th differentiation. It is essential both for efficient interaction between T and B-cells and for normal antibody responses to T-cell dependent antigens. It enhances all basic T-cell responses to a foreign antigen, namely proliferation, secretion of lymphokines, up-regulation of molecules that mediate cell-cell interaction, and effective help for antibody secretion by B-cells.