Background: Successful islet transplantation in type 1 diabetes requires tolerance induction of both allo- and autoreactive T-cell responses. Monoclonal antibodies targeting the CD4 coreceptor on T-helper cells have been shown to be effective in this regard. In type 1 diabetes, there is some evidence to suggest that cytokines such as interleukin (IL)-1 may be involved in beta-cell destruction. The high glucose levels associated with type 1 diabetes are also known to be toxic to beta cells.
Method: The tempo of T-cell and macrophage infiltration into syngeneic islets transplanted into diabetic nonobese diabetic (NOD) mice was examined by immunohistochemistry. We investigated the ability of a nondepleting anti-CD4 monoclonal antibody (YTS177) to induce tolerance to syngeneic islet grafts in female spontaneous diabetic NOD mice and in an adoptive transfer model of diabetes in NOD mice. The spontaneous model was used to test the effect on graft function of perioperative insulin therapy in mice treated with YTS177. The ability of soluble interleukin (sIL)-1 receptor (R) type II (sIL-1RII) to inhibit IL-1 effects in syngeneic islet transplants was also assessed.
Results: Cellular infiltration of CD3 cells and macrophages into the islet graft coincided with loss of graft function in untreated mice. Self-tolerance to beta cells was restored with YTS177, allowing long-term graft survival in a proportion of animals. The use of perioperative insulin therapy increased the number of successful grafts in spontaneously diabetic NOD mice treated with YTS177. The combination of YTS177 with sIL-1RII significantly improved the rates of graft survival compared with graft survival in YTS177-treated spontaneously diabetic NOD mice.
Conclusions: Nondepleting anti-CD4 antibodies restore self tolerance to syngeneic islet transplants in diabetic NOD mice. Insulin therapy improves graft survival in mice treated with YTS177. Preventing the action of IL-1 greatly improves graft survival induced with YTS177.