The extracellular domain (160 amino acids) of mouse CD152 is fused to mouse IgG2a Fc domain in which mutations to the complement (C1q) and FcγR I binding sites of the Fcγ2a fragment render the Fc fusion protein incapable of direct antibody directed cytotoxicity (ADCC) and complement directed cytotoxicity (CDC).
CD152 (CTLA4), a cell surface glycoprotein expressed at low levels on activated T cells, is a high affinity receptor for the costimulatory molecules CD80 (B7-1) and CD86 (B7-2). A related cell surface glycoprotein, CD28, binds to CD80 and CD86 with lower affinity. The soluble CD152/Fc chimeric fusion protein blocks the B7/CD28 signaling pathway by binding to CD80 and CD86.
