[Experimental studies on pancreatic islet xenotransplantation--effect of irradiation on xenografts survival].
The purpose of the present study was to assess the effect of Total Body Irradiation (TBI) and Total Lymphoid Irradiation (TLI) on pancreatic islet xenografts survival. Wistar rats rendered diabetic by intravenous injection of streptozotocin were used as recipients. Golden hamsters were used as islet donors. Pancreatic islets were isolated by the collagenase digestion method. Twelve hundred islet were transplanted into the portal vein of diabetic rats. In untreated controls, the mean graft survival time was 2.9 +/- 0.6 days (n = 7). In TBI of 400 rad treated group, three out of 9 recipients accepted islet xenografts for more than 80 days. TLI of 1200 rad also significantly prolonged graft survival period (30.3 +/- 11.7 days, n = 7, p less than 0.01). Rat anti-hamster lymphocytotoxic antibody titers began to rise on the second day after islets xenografting in untreated and TLI of 400 rad treated recipients. While, elevation of cytotoxic antibody titers was completely suppressed in spite of occurrence of the rejection in TLI of 800 and 1200 rad treated recipients. This may indicate that xenograft rejection in TLI of 800 and 1200rad treated recipients was mediated by cellular immunity rather than humoral immunity.