FOXP3+ regulatory T cells in the human immune system

Regulatory T (TReg) cells are potent mediators of dominant tolerance in the periphery. The study of TReg cells in many models of animal disease has revealed their ability to prevent autoimmune pathogenesis and to restore immune homeostasis but also to promote cancer growth by repressing antitumour immune responses. Such findings have made TReg cells a promising target for clinical application.Confusion as to the mechanism of the identity, function and stability of human TReg cells has, to date, impeded the general therapeutic use of these cells.Several recent studies have suggested that human TReg cells possess functional and phenotypic diversity that has not been previously apparent. Indeed, based on recent findings, forkhead box P3 (FOXP3)+CD4+ T cells can be divided into several functionally unique populations based on their expression of CD45RA, CD45RO, HLA-DR and FOXP3.A more detailed characterization of the ontogeny, phenotype and suppressive function of human TReg cells is needed for the study of TReg cells in the pathophysiology of autoimmune diseases, allergy, transplantation, pregnancy, infection and cancer.Although several issues regarding long term reliability and safety still need to be addressed, TReg cell-based therapy is a promising therapeutic perspective that should be applicable in a wide range of immune diseases.