Prevention of Recurrence of IDDM in Islet-Transplanted Diabetic NOD Mice by Adjuvant Immunotherapy

Insulin-dependent diabetes mellitus (IDDM) involves the destruction of the insulin-producing cells in the islets of Langerhans. One possible cure is by transplanting the islet cells; however, transplanted islets, even between identical twins, are subject to autoimmune destruction by the disease process, resulting in diabetes recurrence. We recently reported that complete Freund's adjuvant (CFA), an immunomodulating agent, prevented development of autoimmune diabetes in the NOD mouse. In this study, we evaluated adjuvant therapy in prevention of autoimmune destruction and rejection of transplanted islets in diabetic NOD mice. After transplantation, untreated syngeneic islet recipients (n = 16) initially became normoglycemic and then hyperglycemic, with a median survival time (MST) of the graft of 17 days. When CFA was administered at the time of transplantation, 11 of 13 CFA-treated syngeneic islet recipients remained normoglycemic long term (> 100 days) with an MST > 107 days. Ten of 11 mice maintained indefinite normoglycemia until the conclusion of follow-up (101 to 172 days). When adjuvant therapy was used in conjunction with allogeneic islet transplantation, graft survival was not extended, with MST being similar to the untreated allogeneic islet recipients (12 [n = 5] and 13 [n = 5] days, respectively). The extended acceptance of second syngeneic islet grafts by CFA-treated mice indicates that the persistent autoimmunity against the transplanted islets can be reversed in the diabetic NOD mice after CFA treatment.