Increased acute bacterial burden and chronic pulmonary pathology in absence of IL-4Rα responsive macrophages following low-dose <i>Mtb</i> H37Rv infection

<p>. Wild-type (BALB/c), IL-4Rα^-/- and IL-4Rα macrophage cell-specific deficient mice (LysM^creIL-4Rα^-/lox) were infected with <i>Mtb</i> H37Rv (100 CFU/mouse) by aerosol (n = 12–13 mice/group). (A) Percentages in body weight change are shown. (B) Mice were sacrificed at 4 and 18 weeks PI to determine bacterial loads in the lungs and spleen. (C) Lung weight indexes are shown. (D) At 0, 4 and 18 weeks PI, formalin-fixed lung sections were stained with H&E. Original magnification: 40X. (E) Lung sections of 5 mice per group were evaluated for pulmonary histopathology scores and quantification of total lesion sizes. N.D. = not detectable. (F) IL-4Rα expression was measured by flow cytometry on alveolar macrophages (SiglecF⁺CD11c⁺) at 0 and 18 weeks PI (*<i>P</i> < 0.05, **<i>P</i> < 0.01). Data shown are representative (A, D, E and F) and pooled (B, C) from two independent experiments.