FOXP3+ regulatory T cells in the human immune system

Forkhead box P3 (FOXP3)(+) regulatory T (T-Reg) cells are potent mediators of dominant self tolerance in the periphery. But confusion as to the identity, stability and suppressive function of human T-Reg cells has, to date, impeded the general therapeutic use of these cells. Recent studies have suggested that human T-Reg cells are functionally and phenotypically diverse. Here we discuss recent findings regarding human T-Reg cells, including the ontogeny and development of T-Reg cell subsets that have naive or memory phenotypes, the unique mechanisms of suppression mediated by T-Reg cell subsets and factors that regulate T-Reg cell lineage commitment. We discuss future studies that are needed for the successful therapeutic use of human T-Reg cells.