TGF-β suppresses the differentiation of antigen-specific CD8 T cells activated in an established chronic infection. (A) Congenically marked WT and KO P14 cells were cotransferred into mice chronically infected with LCMV clone 13 (D45–D60 p.i.). (B) Longitudinal analysis showed the numbers of WT and KO P14 cells in the peripheral blood. (C) Longitudinal analysis of the numbers of WT and KO P14 cells in the spleen, liver, and lungs. Graph shows the mean and SEM. In B and C, paired Student’s t test; *, P < 0.05; **, P < 0.01; ***, P < 0.001. (D) Representative FACS plots show the expression of Tim3 and TCF-1 by WT and KO P14 cells in the spleen at indicated time points after transfer. (E) Representative FACS plots show the expression of Tim3 and CD101 by WT and KO P14 cells in the spleen at indicated time points after transfer. (F–H) Frequencies and numbers of TCF-1⁺ Tim3⁻ stem-like subset (F), Tim3⁺ CD101⁻ transitory subset (G), and Tim3⁺ CD101⁺ exhausted subset (H) among WT and KO P14 cells in the spleen. Paired Student’s t test; *, P < 0.05; **, P < 0.01. Data in B–H are representative of three independent experiments (n = 4–5 each time point per experiment).