Challenge

T regulatory cells (Tregs) play an important role in the induction and maintenance of immu-nological tolerance to self and alloantigens. Recent findings in experimental transplant models have demonstrated that Treg could control and delay allograft rejection. Induction of immune tolerance decreases the risk of acute and chronic graft rejection after solid organ transplantation and can improve transplanted organ survival. Tregs are being tested in trials as a potential therapy in cell and solid organ transplantation. However, as we know, regulatory T cells (Tregs) are crucial for peripheral tolerance and are intimately involved in cancer. The influence of Tregs on cancer progression has been demonstrated in a large number of preclinical models and con-firmed in several types of malignancies. Neoplastic processes trigger an increase of Treg numbers in draining lymph nodes, spleen, blood, and tumors, leading to the suppression of anti-tumor responses. In this review, we summarize some of the critical aspects of the immunoregulatory function of Treg cells in cancer and transplantation and discuss their potential research progress and challenge