Prolongation of allograft survival in diabetic rats treated with cyclosporine by deoxyguanosine pretreatment of pancreatic islets of Langerhans

In vitro pretreatment of islets of Langerhans with deoxyguanosine (dGuo) has been shown to be effective for the prolongation of islet allograft survival in rats. This study evaluates the effect of pretreatment of islets with dGuo transplanted into CsA-treated recipients.] Transplantation of dGuo-treated islets from Wistar rats into diabetic hooded (PVG) rats resulted in 36% graft survival without immunosuppression (dGuo-group) and 89% islet survival after a short course of cyclosporine was used in recipients (dGuo + CsA group). In contrast, transplantation of untreated islets into rats without immunosuppression (controls) and with CsA (CsA group) immunosuppression resulted in 0 and 56% survival, respectively. The differences in graft survival between dGuo versus control group (P less than 0.001), (dGuo + CsA) versus control group (P less than 0.0001), and CsA versus control group (P less than 0.002) are statistically significant. Donor-strain skin-graft challenge failed to induce rejection of transplanted normoglycemic rats in (dGuo) and (dGuo + CsA) groups. The results indicate that a state of immunologic unresponsiveness may have been induced in the recipients of dGuo-treated islets, and further treatment with CsA synergistically prolongs islet survival in fully mismatched rats.