Indefinite allograft survival induced by the combination of multiple donor-specific transfusions, cyclosporine, and an anti-T cell monoclonal antibody in a protocol relevant to cadaveric organ transplantation. The importance of prolonged posttransplant cyclosporine coverage.

A single donor specific transfusion (DST) 24 hr pretransplant and Cyclosporine (CsA) are synergistic in inducing prolongation of allograft survival. This synergy was further potentiated by giving 3 additional DSTs at weekly intervals posttransplant, or by the additional administration of a small dose of the anti-T cell monoclonal antibody OX-52 24 hr pretransplant to the above protocol. This study determined whether indefinite survival can be achieved in the ACI-to-Lewis heart allograft model by combining an anti-T cell monoclonal antibody, 4 DSTs given once 24 hr pretransplant and weekly 3 times posttransplant, and CsA. CsA was given daily for 28 days or 60 days posttransplant. The dose consisted of CsA 5 mg/kg/day starting 24 hr pretransplant and continuing until day 7 posttransplant and followed by 2.5 mg/kg/day for either 21 more days (total CsA days = 28 days) or 53 days (total CsA days = 60 days). The anti-T cell monoclonal antibody OX52 (200 micrograms i.v.) was given once 24 hr pretransplant. DST (1 ml) was given 24 hr pretransplant and on days 7, 14, and 21 posttransplant. Low-dose CsA for 28 days never induced indefinite allograft survival. CsA for 60 days, however, resulted in the occasional indefinite allograft survival (> 1 year) even in this difficult model. The addition of DST 24 hr pre- and posttransplant on days 7, 14, and 21 to both 28 days and 60 days of CsA further prolonged allograft survival. The best survival was seen in the group given DST 24 hr pre- and on days 7, 14, and 21 posttransplant and 60 days of CsA, with all the allografts surviving beyond 100 days of CsA, with all the allografts surviving beyond 100 days and more than 50% surviving indefinitely (> 1 year). The addition of a single dose of OX52 24 hr pretransplant to the multiple DSTs and 28 days of CsA protocol significantly improved indefinite allograft survival but its influence was less dramatic when given to the multiple DSTs and 60 days of CsA protocol. This beneficial interaction between CsA, DST, and an anti-T cell MoAb offers a clinically applicable protocol for both living donor and cadaveric organ transplantation in inducing donor-specific hyporesponsiveness, and further investigations are warranted.