Transplantation tolerance in primates following total lymphoid irradiation and allogeneic bone marrow injection: I. Orthotopic liver allografts

Fractionated total lymphoid irradiation (TLI) and allogeneic bone marrow (BM) injection have been reported to produce stable chimerism without graft-versus-host disease (GVHD) in inbred mice and rats and mongrel dogs, and transplantation tolerance for skin and heart grafts in rodents. This concept has been studied in outbred chacma baboons receiving orthotopic liver allografts with the use of five different irradiation protocols. Eight fractions of 200 rad to the whole torso, followed immediately by allogeneic BM injections, and liver grafts from the BM donors 3 to 4 weeks later resulted in markedly prolonged survivals of 63 to 106 days in four baboons (median survival of untreated controls 19 days). Only one of the four animals died directly from the effects of rejection. BM chimerism was demonstrated in two baboons. There were no clinical or histological signs of GVHD in any of the animals. Two fractions of TLI, totaling 800 rad, 23 hr apart and followed immediately by BM injection and liver grafting resulted in profound thrombocytopenia and death from intraperitoneal hemorrhage in four of five baboons. In one animal BM injection and liver transplantation were delayed for 75 days. The baboon is still alive more than 6 months later. Three groups received single doses of 300, 400, and 500 rad to the whole torso, followed by allogeneic BM injections 1 and 2 weeks later, and liver transplants from their BM donors after an additional 3 to 4 weeks. The four baboons receiving 300 rad survived for 42, 86, 123, and >180 days. Two of the four baboons receiving 400 rad died of septic intraabdominal complications with minimal or no evidence of rejection. Four of the five baboons receiving 500 rad died from rejection. Pulmonary shielding was used in the latter groups only, and this may have resulted in inadequate axillary and mediastinal lymphoid irradiation. TLI and BM injection produces substantial tolerance for liver allografts in the baboon. Further evaluation of irradiation protocols, and dosage and timing of BM injections is indicated. © 1980 by The Williams and Wilkins Co.