IL2RA and autoimmune disease: The importance of γc cytokines to tTreg development is highlighted by the absence of this population from the thymus and periphery of IL-2R-γc knockout animals (Fontenot et al., 2005b) and spontaneous development of autoimmune diseases in mice lacking IL-2Rβ (CD122), which can be prevented by infusion of donor Tregs (Suzuki et al., 1995; Malek et al., 2002).