Fig. 9: Brain-infiltrating CD4 T cells drive microglia proliferation during infection.

a Number of Ki67⁺ microglia and b IAMs (CD206⁺MSR1⁺ microglia) at day 0 or day 8 post-infection in wild-type (n = 6 mice; filled symbols/bars) and Rag2^−/− (n = 6 mice; open symbols/bars) mice. Data pooled from two independent experiments, presented as mean +/- SEM and analysed by two-way ANOVA. **P = 0.002, ****P < 0.0001. c Fungal brain burdens in wild-type and Rag2^−/− mice at day 8 post-infection in mice infected with C. neoformans strain H99 (n = 10 wild-type mice, n = 7 Rag2-deficient mice) or C. neoformans strain Zc1 (n = 10 wild-type mice, n = 9 Rag2-deficient mice), and d number of Ki67+ microglia at day 8 post-infection in mice infected with C. neoformans strain H99 (n = 10 wild-type mice, n = 7 Rag2-deficient mice) or C. neoformans strain Zc1 (n = 10 wild-type mice, n = 9 Rag2-deficient mice). Data pooled from two independent experiments and analysed by two-way ANOVA. **P = 0.0052, ***P < 0.0001. e Example immunofluorescence of Ki67 and DAPI labelling in brain sections from wild-type and Rag2^−/− mice at day 8 post-infection. Infection lesions are outlined with white dashed lines. Images were quantified by randomly selecting three parenchymal regions near sites of infection within each brain section, and dividing the pixel intensity of the Ki67 stain by the pixel density of the DAPI stain for each analysed region to determine the Ki67/DAPI ratio. Three mice were analysed for wild-type mice (9 regions sampled) and 4 Rag2^−/− mice analysed (12 regions sampled). Different symbol shapes show matched regions for each mouse. Data analysed by unpaired t-test, presented as mean +/- SEM. **P < 0.008. f Total number of CD4 T cells, Ki67⁺ microglia and IAMs in the brains of mice at day 8 post-infection, treated with either isotype control antibody (n = 6 mice; filled symbols/bars) or anti-CD4 depleting antibody (n = 6 mice; open symbols/bars). Data pooled from two independent experiments and analysed by unpaired t-tests. *P = 0.0447 (IAMs), *P = 0.0364 (Ki67+ microglia), **P = 0.0059. g Weight loss, relative to weight at start of experiment, of isotype control or CD4-depleted mice (n = 9 per group) during infection. Data shown as mean +/- SEM, pooled from three independent experiments. Data analysed by two-way ANOVA with Bonferroni correction, **P = 0.0045. h Fungal brain burdens at day 8 post-infection in isotype or CD4-depleted mice (n = 6 mice per group). Data pooled from two independent experiments. In all box-and-whisker plots, whiskers refer to the maximum/minimum values, the box refers to interquartile ranges, the centre line refers to the mean.