PROLONGED SURVIVAL OF RAT HEPATIC ALLOGRAFTS AFTER TOTAL-BODY IRRADIATION OF THE DONORS

The effect of total-body irradiation of the donor on hepatic allograft survival was studied in the rat, with ACI(RT1a) as the donor and LEW(RT1l) as the recipient. LEW recipients of ACI liver transplants experienced severe acute rejection, with a mean survival of only 10.2+/-0.3 days. The doses of irradiation were 450, 750, and 1000 rads administered 24 hr prior to harvesting or subsequent transplantation. TBI with a dose of 750 rads significantly prolonged the survival of the hepatic allograft to 30.3+/-1.7 days, without concomitant immunosuppression. However, neither 450 rads nor 1000 rads of TBI resulted in successful suppression of graft rejection. TBI appeared to have a beneficial effect on hepatic allograft survival and to have no deleterious effect on isograft survival, suggesting a possible modulation of the immunogenicity of the donor organ. Although the cause of this beneficial effect is not clear, TBI with a dose of 750 rads 24 hr prior to organ harvest seems to be optimal to eliminate-antigen presenting cells in the donor organs.