Effect of cyclosporine and irradiation on experimental pancreatic allografts in the primate

The present study assessed the effectiveness of cyclosporine (CSA) and subtotal marrow irradiation (TL1) alone, and CSA in combination with TL1 in a primate segmental pancreatic allotransplantation model. Continuous administration of CSA 25 mg/kg/day and 50 mg/kg/day resulted in mean graft survival of 21.5 days and 24.5 days, respectively. Administration of fractionated TL1 800 rad (8 Gy) and 1,000 rad (10 Gy) alone resulted in mean graft survival of 13.3 days and 14.5 days, respectively. Of 20 animals that received TL1 1,000 rad (10 Gy) and CSA 25 mg/kg/day orally for 5 days then 10 mg/kg/day intramuscularly indefinitely, 3 had graft survival of greater than 100 days. Likewise, of a group of 15 animals that received TL1 800 rad (8 Gy) and combined indefinite administration of CSA, 6 had graft survival of greater than 100 days. Although CSA and TL1 administration alone produced modest pancreatic allograft survival, a combination of IL1 (800 or 1,000 rad) and CSA resulted in highly significant segmental pancreatic allograft survival in the primate.