Neonatal induction of allogeneic tolerance prevents T cell‐mediated autoimmunity in NOD mice

Diabetes in the NOD mouse strain is a genetically programmed T cell‐mediated autoimmune process that is directed against an as yet unknown antigen target(s) on pancreatic β cells. To investigate whether the course of the autoimmune disease could be altered by immune manipulations of the T cell repertoire, we have induced allogeneic tolerance by injecting F1 semiallogeneic spleen cells into NOD neonates. This procedure resulted in a significant protection against both insulitis and diabetes. However, although it requires the induction of tolerance, as shown by the failure of non‐tolerizing irradiated cells to prevent autoimmunity, protection appeared to be independent of the major histocompatibility complex haplotypes of the F1 spleen cells injected at birth, e.g. (C57BL/6 x NOD)F1, (CBA/Ca x NOD)F1 or (BALB/c x NOD)F1 cells. In addition, a similar degree of protection was induced, whether the tolerant state, as assessed by mixed lymphocyte reaction studies in vitro, was of short duration, ∼6 weeks, or lasted for more than 12 weeks. Putative veto or suppressor functions of chimeric T cells were ruled out, since mice tolerized with T cell‐depleted F1 spleen cells were equally protected.