Figure 1. Cdk5 is essential for IL-6 suppression of TGF-β induced Foxp3 expression in CD4+ T cells.
A) Naïve CD4+ T cells were isolated from wild-type mice and stimulated with anti-CD3 and anti-CD28, with or without TGF-β, in the presence or absence of IL-6 and the Cdk5 specific inhibitor CIP as indicated for 72 hours. Foxp3 protein expression and numbers of Foxp3+ cells were quantified by flow cytometry. B) Wild-type and Cdk5-deficient T cells were stimulated with anti-CD3 and anti-CD28, with or without TGF-β and IL-6 as indicated for 72hrs. Foxp3 protein expression and numbers of Foxp3+ cells were quantified by flow cytometry. C) Foxp3 mRNA expression levels in T cells activated in the presence or absence of TGF-β, IL-6 and CIP for 16hrs were analyzed with real time RT-PCR. D) Both Cdk5+/+ T cells and Cdk5−/− T cells were treated with or without TGF-β and IL-6 for 16hrs, and subsequently Foxp3 mRNA expression levels were examined using real time RT-PCR analysis.