MyD88-dependent influx of monocytes and neutrophils impairs lymph node B cell responses to chikungunya virus infection via Irf5, Nos2 and Nox2
C57BL/6 mice were left untreated or treated with 300–500 μg of IgG2b isotype control mAb or anti-Gr-1 mAb via intraperitoneal injection one day prior to inoculation with 103 PFU of CHIKV 181/25 or AF15561 in the left footpad. (A) Representative flow cytometry plots and percentages of (B) CD11b+Ly6Chi monocytes or (C) CD11bhiLy6C+Ly6G+ neutrophils in the blood. (D) Representative flow cytometry plots and numbers of (E) CD11b+Ly6Chi monocytes or (F) CD11bhiLy6C+Ly6G+ neutrophils in the dLN. Data are combined from two independent experiments (n = 3 (mock) to 7 per group). At 5 dpi, the dLN was analyzed for (G) total cells, (H) CD19+B220+ B cells, (I) TCRβ+CD4+ T cells, and (J) TCRβ+CD8+ T cells. Data are combined from 3 independent experiments (n = 4 (mock) or 11 per group). (K) Frozen dLN sections were stained for ERTR7+ stromal cells (red), B220+ B cells (blue), or CD8+ T cells (green). Errors bars represent mean ± SEM. Data in (G-J) are combined from 3 independent experiments. Data in (K) are representative of 2 independent experiments with 4–5 LNs per group. Statistical significance was determined by one-way ANOVA with Tukey’s post-test (*, P < 0.05; **, P < 0.01; ***, P < 0.001).