CD80 and melanoma: Studies have shown that the addition of anti-CTLA-4 monoclonal antibody leads to increased T-cell proliferation, presumably by blocking the interaction of CTLA-4 with its natural ligands CD80 and CD86.2 Ipilimumab is a human monoclonal IgG1 antibody against CTLA-43 that is clinically used for the treatment of advanced melanoma, given studies that have demonstrated its ability to prolong survival.