Definition

A humanized, non-Fc receptor (FcR)-binding IgG2 monoclonal antibody (MoAb) directed against CD3 with potential immunosuppressive activity. Visilizumab binds to invariant CD3 epsilon, one of the non-covalently-associated subunits of T-cell receptors (TCRs) on activated T cells. Upon binding to the TCR/CD3 complex, visilizumab induces apoptosis, which may result in the selective clonal deletion of activated pathogenic T cells. This MoAb is engineered with a substitution at amino acid residues 234 and 237 (Val3Ala) within the IgG2 Fc arm, rendering it unable to bind to type II FcRs; accordingly, this agent is less likely to activate type II FcR-expressing resting T cells.