Description: The eBioG4.18 monoclonal antibody recognizes the rat CD3 protein. CD3 is a critical component of the T-cell receptor (TCR) and is a marker of the T-cell lineage. CD3 is a complex of several subunits and, upon binding of a TCR ligand, participates in transduction of signals from the TCR to the nucleus which results in a variety of cellular responses including transcription of IL-2 and clonal expansion. in vitro, immobilized G4.18 monoclonal antibody has been demonstrated to activate T cells, while soluble G4.18 inhibited allogeneic mixed-lymphocyte proliferative responses and cell-mediated cytotoxicity to allogeneic target cells. in vivo, G4.18 was demonstrated to induce long-term specific tolerance to an organ allograft.