Regulatory T cells in transplantation: transferring mouse studies to the clinic.

Switching the balance from rejection of major histocompatibility-mismatched grafts toward long-term tolerance of donor grafts, with the need for minimal immunosuppressive drugs, is a major transplantation goal. Regulatory T cells (Treg) can induce and maintain antigen-specific immune tolerance and facilitate allogeneic graft survival successfully in animals. This review will focus on the valuable insights experimental mouse models have given us into the effects of currently used immunosuppressive reagents on Treg, the Treg transcription factor forkhead box P3, and strategies to expand or induce alloantigen-reactive Treg in vivo and in vitro. These have facilitated the translation of strategies for promoting transplantation tolerance towards a new clinical era.