Fig. 4: Itgβ8^pos Tregs promote TGF-β signaling in intra-tumor T cells affecting their anti-tumor response.

a, b Foxp3^Ctrl mice (black) and Foxp3^ΔItgβ8 animals (red) were injected i.d. with B16 cells. Tumors and draining lymph nodes(tdLN) were harvested 15 days later and analyzed by flow cytometry. Representative histogram of the levels of phosphorylation of SMAD2/3 (p-SMAD2/3) in tumor-infiltrating T cells (a) percentage of cells with high phosphorylation of SMAD2/3 are indicated on each histogram as well as FMO control. Graphs demonstrate the mean of fluorescence intensity (MFI) ± SD in T cells (a). Data are representative of two independent experiments with 4–6 mice per group. c–g Purified Tregs from either Foxp3^Ctrl mice or Foxp3^ΔItgβ8 mice were adoptively transferred with Foxp3^neg T cells (CD3^posGFP^neg) from either CD4-Cre;Stop^fl/fltgfbr1^CA_;Foxp3^GFP mice (TGFβRI^CA) or their littermate controls (TGFβRI^WT) in CD3ε^KO mice. Ten days later, recipient mice were injected i.d. with B16 cells and their tumors were analyzed 16 days after their implantation by flow cytometry. d Representative contour plots of CD107 cell surface expression and GzB production by tumor-infiltrating CD8^pos T cells are illustrated and percentages of each population mentioned populations are on the counterplots. e Graphs illustrate the percentage of GzB^pos CD107^pos cells and of CD107^pos cells among CD8^pos T cells infiltrating the tumors. Six mice of each group from two independent experiments were analyzed. Data are presented as mean ± SD. f Representative graph illustrating the size of the tumors at different days tumor cell post-injection. n = 5 mice per group. g Graph represents the tumor size at the end of the experiments. Data are representative of three independent experiments with five recipient mice per group. Means are shown ± SD. b P = 0.0283 (*)/P = 0.3929 (ns), e P = 0.0065 (**)/P = 0.3133 (ns)/P = <0.0001 (****)/P = 0.0002 (***), g P = <0.0001 (****)/P = 0.5052 (ns)/P = <0.0001 (****)/P = 0.0007 (***). *P < 0.05, **P < 0.01, ***P < 0.001 was determined by two-tailed Mann–Whitney test. ns statistically not significant.