Figure 6. CCR2 and monocyte recruitment are essential for a successful granuloma response to C. violaceum.

Wildtype (WT) and Ccr2^−/− mice were infected intraperitoneally (IP) with 1×10⁴ CFU C. violaceum. (A) Survival analysis of WT (N = 10) and Ccr2^−/− (N = 9) mice. Two experiments combined. Mantel-Cox test, ****p<0.0001. (B-K) Livers and spleens were harvested 5 days post-infection (DPI). Bacterial burdens in the (B) liver and (C) spleen of WT and Ccr2^−/− mice. Two experiments combined. Each dot represents one mouse. (B) Two-tailed t test (normally distributed data); ***p=0.0002. (C) Mann-Whitney (abnormally distributed data); **p=0.0012. Dotted line, limit of detection. Solid line, median. (D) Gross images of WT and Ccr2^−/− livers 5 DPI. (E) Gating strategy for analysis of neutrophil (Ly6G⁺) and macrophage (CD68⁺) numbers via flow cytometry. Liver samples from infected mice shown. Frequency of CD68⁺ macrophages from single cell gate in the (F) liver, (H) spleen, and (J) blood. Frequency of Ly6G⁺ neutrophils from single cell gate in the (G) liver, (I) spleen, and (K) blood. (F-K) Three experiments combined using only female mice. Each dot represents one mouse, with 10,000 events collected per sample. Two-way ANOVA (for multiple comparisons to assess genotype and infection); key comparisons and p-values shown. Line represents mean ± standard deviation.