IL-10 signaling in recall responses promotes CD8 ⁺ T cell effector function. (A–C) Graphs show quantification of: (A) lymphocyte lineages (NK, B, CD4⁺, and CD8⁺ T cells), (B) CD8⁺ T cell subsets, and (C) IFN-γ production by lung CD8⁺ T_RM and T_EM subsets from mice treated with αIL-10R antibody (purple) or IgG control (blue) at 4 dpi. Data are compiled from four independent experiments (n =12–16 mice per group). Statistical significance was determined by Student’s t test. (D) IFN-γ content in the BAL of control- and αIL-10R–treated mice at 4 dpi. Results are representative of two independent experiments with n = 9 in each group. Statistical significance was determined by Student’s t test. (E) IFN-γ production by lung CD8⁺ T cells stimulated ex vivo with anti-CD3/anti-CD28–coupled beads (αCD3/28)±IL-10 shown in representative flow cytometry plots (left) and compiled results from two independent experiments with n = 11 mice per group (right). Statistical significance was determined by Student’s paired t test. For A–F, boxes indicate the interquartile range with a line drawn at the mean; whiskers indicate the minimum and maximum values. ****P ≤ 0.0001; ***P ≤ 0.001; **P ≤ 0.01; *P ≤ 0.05.