Figure 4.

CD25⁺CD8⁺ T cells in LCMV‐infected mice express the highest level of PD‐1 and associate with CD8⁺ T‐cell‐mediated pro‐inflammatory immune response. Mice were intraperitoneally injected with LCMV Armstrong and analysed at day 8 post‐infection. (a) Flow cytometric plots showing representative CD25⁺PD‐1⁺ expression on splenic CD8⁺ T cells from mice of the indicated group (left) and statistics between G1 and G2 mice from Figure 3e (right). (b) Correlations between immune variables in the module for pro‐inflammatory T‐cell response and weight changes. Individual mice in G1 and G2 from Figure 3e are labelled in green and red respectively. (c–e) Wild‐type (WT, N = 5–8) and CD8‐deficient (CD8‐KO, N = 3–8) mice were intraperitoneally injected with LCMV Armstrong and analysed at day 8 post‐infection. Serum sCD25 of individual mice are shown (c). Weight changes of the indicated group shown as mean ± SD (d). Comparisons of tissue histopathology by haematoxylin and eosin (H&E) staining showing lower cellularity of infiltrated cells, reduced necrosis and better tissue integrity in CD8‐KO mice as compared to WT mice (e). Data are representative of two or three independent experiments. P‐values were calculated by the Mann–Whitney U‐test (a) and Spearman's rank correlation test (b). P‐values < 0.05 are considered to be statistically significant.