PROLONGATION OF PRIMATE CARDIAC ALLOGRAFT SURVIVAL BY TREATMENT WITH ANTI-CD40 LIGAND (CD154) ANTIBODY1

Abstract

We evaluated whether a humanized anti-CD154 antibody (hu5c8) prolongs primate cardiac allograft survival. Heterotopic cardiac allografts were performed between MHC class II-mismatched cynomolgus monkeys. Survival was compared between groups treated with a perioperative dosing of hu5c8 (group 1; n=6), sustained dosing with hu5c8 (group 2; n=3), and control regimens (n=4). All recipients received fresh donor-specific transfusions during surgery. Median graft survival was 49 days (range 14 to 56) in group 1 and 106 days (range 56 to 245) in group 2, compared with 5 days (range 5 to 6) for controls (P<0.05 for all comparisons). Lymphocytic infiltrates were often present in hu5c8-treated grafts with stable contractility. Donor-specific mixed lymphocyte reaction was generally preserved. Vasculitis and cellular intimal proliferation were prevalent in rejected grafts but occurred later and were less prevalent in group 2. Anti-CD154 antibody markedly prolongs the survival of cardiac allografts in primates and is well tolerated. Sustained dosing with hu5c8 yielded improved survival and may be associated with a lower incidence of vascular pathology. We conclude that hu5c8 therapy is an effective approach for inhibiting acute cardiac allograft rejection in primates.