1B), which is compatible with previous reports [15] and the fact that CD4+CD25−LAG3+ Treg cells hardly expressed Foxp3 protein [21]. When we added IL-27 to naïve CD4+ T cells stimulated with plate-coated anti-CD3ε and anti-CD28 mAbs, Egr-2 protein was clearly detected by intracellular staining. This induction was abolished in Egr-2-deficient CD4+ T cells cultured with IL-27 and also in IL-27Rα (WSX-1)-deficient CD4+ T cells (Fig. 1C). Interestingly, LAG-3

was predominantly induced in B6 WT CD4+ T cells expressing Egr-2, and IL-27 alone did not induce Egr-2 in the absence of TCR stimulation. IL-27 more efficiently induced Egr2+LAG3+ cells than the other IL-12 family cytokines, IL-12 and IL-23 (Fig. 1D). Although IL-2 is required for IL-27-induced IL-10 expression through Blimp-1 in CD8+ T cells [26], IL-2 by itself Z-VAD-FMK supplier could not induce Egr2+LAG3+ cells and showed no additive effect on IL-27-induced Egr-2 and LAG-3 expressions (Fig. 1D). No significant association was seen between the extent of cell division and the amount of Egr-2 expression, while Egr-2 induction was limited to proliferating cells (Fig. 1E). Multiple observations support the idea that Maraviroc ic50 Blimp-1 regulates T-cell responsiveness by attenuating IL-2 production. IL-2 production in Blimp-1-deficient CD4+ T cells is elevated by stimulation via TCR [18]. As IL-2 signaling induces Blimp-1 transcription, Blimp-1 makes a negative feedback loop for

Il2 transcription in T cells [19]. Recently, it was shown that Blimp-1 positively regulates IL-10 production in CD4+ T cells [18, 27]. Blimp-1 is required for IL-10 production and high ICOS expression in CD4+CD25+Foxp3+ Treg cells [28]. Therefore, the role of Egr-2 and Blimp-1 in IL-27-induced

IL-10 production was examined using naïve CD4+ T cells from Egr-2 CKO (Egr2fl/fl-CD4-Cre+) and Blimp-1 CKO (Prdm1fl/fl-CD4Cre+) mice. Consistent with our previous observation that the forced expression of Egr-2 induced the high mRNA expression levels of Blimp-1 in CD4+ T cells [21], Egr-2-induction by IL-27 was not affected in the absence of Blimp-1 (Fig. 1C). In CD4+ T cells both from Egr-2 CKO mice and Blimp-1 CKO mice, the induction of Il10 transcription and IL-10 protein expression by IL-27 was impaired Clomifene (Fig. 2A and B), and these inductions were not observed in CD4+ T cells from WSX-1 KO mice (Fig. 2A and B). Moreover, Blimp-1 mRNA induction by IL-27 was also impaired in Egr-2-deficient CD4+ T cells (Fig. 2A). This result suggested that Egr-2 is essential for IL-10 production via Blimp-1 expression in IL-27-stimulated CD4+ T cells. When we analyzed the induction of IL-10 and Blimp-1 mRNA expressions by other IL-12 family cytokines, IL-12 showed only marginal induction of IL-10 and Blimp-1 mRNA expressions and IL-23 induced no up-regulation of IL-10 and Blimp-1 mRNA expressions (Fig. 2C). We also found that IL-2 had no additive effect on IL-27-induced IL-10 and Blimp-1 mRNA expressions in CD4+ T cells (Fig. 2C).