Figure 6. miR-155 is required for MDSC-mediated Treg induction.

(A) Representative dot plots of Foxp3 expression in LLC1-OVA tumor-infiltrating CD4⁺ cells. Percent Foxp3⁺ cells is indicated within plots and summarized. (n= 5). (B) WT or miR-155^−/− CD4⁺CD62L⁺ naïve T cells were transferred into CD45.1 mice followed by a s.c. injection of LLC1-OVA cells. The conversion of transferred T cells to Foxp3⁺ cells (CD45.2⁺) in DLN and spleen from LLC1-OVA tumor-bearing mice were detected by flow cytometer 9 d after tumor cell injection. The levels of converted Foxp3 expression are determined by mean fluorescent intensity (MFI). Endogenous Foxp3⁺ cells (CD45.1⁺) from host mice were shown as controls. (C) WT and miR-155^−/− MDSCs from LLC1 tumor-bearing mice were cocultured with OT-II splenocytes at a 1:4 ratio for 5 days in the absence or presence of TGF-β, and induced CD25⁺Foxp3⁺ cells among total CD4⁺ T cells were subsequently determined by flow cytometry. ***, P<0.001. Data are representative of 2 independent experiments.