P38 MAP Kinase Signaling Is Required for the Conversion of CD4+CD25− T Cells into iTreg
Figure 3
Signaling via p38 MAP kinase is required for the in vitro conversion of CD4+CD25− T cells into TGF-beta1-induced Foxp3+ Treg (Ti Treg).
CD4+CD25− T cells were activated with plate bound anti-CD3 mAb (2 µg/ml) and soluble anti-CD28 mAb (2 µg/ml) for 4 days in the presence or absence of TGF-beta1 (2 ng/ml). Kinase inhibitors were added every 12 h (SB203580 (10 µM), SP600125 (10 µM), PD89059 (50 µM)). A: Schematic experimental procedure. Ti Treg: TGF-beta-induced Treg. B: Foxp3-expression and in vitro suppressor assay using CD4+CD25− CFSE-labelled responder T cells isolated from spleen and suppressor T cells generated by in vitro conversion as described above. Cells were washed three times before adding to the culture. Responder and suppressor cells were added at the indicated ratios [×105]. Data are representative of three independent experiments using SP600125, PD89059, SB202190 and five independent experiments using SB203580.