Cutting edge: IL-27 is a potent inducer of IL-10 but not FoxP3 in murine T cells

The cytokine IL-27 is important for restricting inflammation in response to a wide variety of immune challenges. In this study, we demonstrate that IL-27 induces expression of the anti-inflammatory cytokine IL-10 by CD4(+) and CD8(+) T cells. IL-27 relied upon the Th1 transcription factor STAT1 to induce IL-10(+)IFN-gamma(+)FoxP3(-) Th1 cells, which were recently shown to be key negative regulators during certain infections. IL27ra(-/-) mice generated fewer IL-10(+) T cells during both Listeria monocytogenes infection and experimental autoimmune encephalomyelitis. The data presented here indicate a novel mechanism for the induction of IL-10 expression by T cells and provide a mechanistic basis for the suppressive effects of IL-27.