Fig. 4: TIGIT controls the differentiation of Th1 and Th17 cells in vitro and in vivo.

a–n Naive CD4⁺ T cells were isolated from Tigit^−/− or Tigit^+/+ mice. The cells were subjected to culture conditions for Th1, Th2, Th17 and Treg cell differentiation for 5 d. a–d Th1 condition: T-bet, GATA3, and IFNγ expression in CD4⁺ T cells was measured by flow cytometry, and representative contour plots were shown. e–h Th2 condition: flow cytometric analysis of GATA3 and IL-4 expression in CD4⁺ T cells and representative contour plots. i–l Th17 condition: RORγt and IL-17A expression in CD4⁺ T cells measured by flow cytometry. m, n Treg condition: FoxP3 expression in CD4⁺ T cells measured by flow cytometry and representative contour plots. o Scheme of the mouse experiment. EAM was induced as described in Fig. 2. Each Rag1^−/− recipient mouse was injected intravenously with 2 × 10⁶ naive CD4⁺ T cells, and EAM induction was performed. p–s The expression of T-bet, RORγt, IFNγ, and IL-17A in CD4⁺ T cells from mice that received Tigit^−/− or Tigit^+/+ cells was measured via flow cytometry. Representative contour plots were shown. t Schematic employed to visualize that TIGIT deficiency enhances Th1 and Th17 differentiation, resulting in severe muscle infiltration. Original magnification: ×200. b, d, j, l, q, s, n = 5; for f, n = 4; and for h, n n = 6 biological independent samples. All data are presented as the mean ± SEM. Statistics were done by two-tailed unpaired Student’s t test.