Identification of a human Th1-like IFNγ-secreting Treg subtype deriving from effector T cells

► IFNγ(+)foxp3(+)Tbet(+) adaptive Treg (iTreg) emerge from effector T cells in vitro. ► They suppress like natural Treg: cytokine-independent and cell contact-dependent. ► Although secreting IFNg themselves they suppress IFNγ-secretion in effector cells. ► TGF-β blockade increases growth of IFNγ(+)iTreg but does not abrogate suppression. ► IFNγ(+)Treg could be isolated from tonsils of patients with recurrent infections.