CD8+ gammadelta T regulatory cells mediate kidney allograft prolongation after oral exposure to alloantigen.

The long term goal of immunological therapy for transplantation is to induce antigen specific unresponsiveness. One approach of significant current interest is the induction of T regulatory (Treg) cells that downregulate immune responses in an antigen specific manner. In this study, we examined the nature of the immunological regulation initiated by oral exposure to alloantigen. We previously demonstrated that feeding of allogeneic donor splenocytes significantly prolongs kidney allograft survival in rats. Purified CD8+ graft infiltrating cells (GIC), but not CD4+ GIC transfer graft prolongation to naïve animals demonstrating the presence of a CD8+ Treg population in the graft. In this study, we provide evidence that is consistent with a hypothesis that the CD8+ Treg generated by oral exposure to alloantigen is an IL-10 secreting, gammadelta TCR+ T cell.