Regulatory T Cells and Transplantation Tolerance

In the past decade, several types of regulatory T cells (Tregs) have been identified to play a pivotal role in the control of autoimmunity and transplantation tolerance in rodents and in human beings, including innate regulatory NKT cells and γδ T cells, naturally occurring FoxP3 expressing CD4+CD25+ T cells, and in-vitro induced Tregs including interleuking-10 (IL-10)-secreting Tr1 CD4+ T cells, TGF-β–producing Th3 CD4+ T cells, anergic CD4+ T cells, CD8+CD28− and CD3+CD4−CD8− T cells. Recent studies have shown that innate and adaptive Tregs may be linked and act in concert to mediate immunosuppression. As our understanding of regulatory T cell populations has substantially advanced, compelling evidence support the prospect that in-vitro expanded, patient-tailored Tregs with indirect anti-donor allospecificity could be potential reagents as adoptive cell therapy for individualized medicine to promote clinical transplantation tolerance.