Abstract: Recently, it is reported that regulatory T cells (Tregs) can be reprogrammed into a novel population [interleukin (IL)-17+ Foxp3+ T cells] phenotypically and functionally resembling Th17 cells under complicated cytokine circumstances. IL-17+ Foxp3+ T cells are characterized by production of IL-17 and expression of retinoic acid receptor related orphan receptor (ROR)γt, demonstrating dual functions in immune response and providing novel insight into the interconnection between Tregs and Th17 cells. In this review, we lay emphasis on the phenotype features, origination, differentiation and the pleiotropic functions of IL-17+ Foxp3+ T cells. Furthermore, we summarized the functions of IL-17+ Foxp3+ T cells in inflammatory disease and tumor microenvironment.

Key words: T- lymphocytes, regulatory, interleukin- 17, inflammation, neoplasms,  review, IL- 17 + Foxp3 + T cells, RORγt