Fig. 6: Brain-resident macrophages exhibit elevated levels of phagocytic markers in fetal brains from high-dose IAV dams.

A Representative coronal sections of E16.5 fetal brains stained with Iba1 (red) and CD68 (green). Scale bars = 100 µm. Brain-resident macrophages (Iba1⁺ cells) showed increased phagocytic capacity in X31_hi fetal brains when evaluating B total counts of Iba1⁺CD68⁺ cells per mm² and C percentage of Iba1⁺ cells that were also CD68⁺. D–G Parenchymal Iba1⁺ cells, which approximate microglia, and meningeal Iba1⁺ cells (meningeal BAMs) did not demonstrate a dose-dependent increase in phagocytic capacity. H Elevated counts of Iba1⁺CD68⁺ choroid plexus BAMs did not persist when evaluated as a I percentage of Iba1⁺ cells that were also CD68⁺. IAV = influenza A virus, dpi = days post-inoculation, E = embryonic day, BAM = border-associated macrophage, Con = saline control, X31_mod = IAV-X31 10³ TCID₅₀, X31_hi = IAV-X31 10⁴ TCID₅₀, Groups were compared using one-way ANOVA with Tukey post hoc for multiple comparisons. Data are means ± SEM; * = p < 0.05; dots represent one representative fetus per litter; n = 9–10 per treatment group. See Supplementary Table S11 for complete statistical analysis of all data collected for this figure (individual mean ± SEM per group, p-values, hypothesis test used, and test statistic).