CD4 + Regulatory T Cells Control T H 17 Responses in a Stat3-Dependent Manner

Abstract

Outfoxing Immune Excess: Immune responses are kept in check by Foxp3-expressing CD4 ⁺ -regulatory T cells (T _regs ) through a variety of mechanisms. Expression of specific transcription factors directs T _reg responses into distinct T helper cell lineages; however, the transcription factors that regulate particular helper lineages have not been completely characterized. Chaudhry et al. (p. 986 , published online 1 October) show that the transcription factor Stat3, that is required for the initial differentiation of T _H 17-effector T cells, is also required for T _reg cell-mediated suppression of T _H 17-mediated immune responses. Mice carrying a T _reg cellspecific deletion in Stat3 succumb to an intestinal inflammatory disease driven by uncontrolled T _H 17 responses. Thus, different classes of immune responses can result from the expression of helper lineage–specific transcription factors.