Figure 4.

Airway mucus occlusion, acidophilic pneumonitis and alveolar bronchiolization 49 days after SeV infection. (a) The lungs of mice treated or not with O/P, then challenged or not with SeV 1 day later, and then killed 49 days later with lungs inflated with 10% formalin to 20 cm H₂O pressure. Arrowheads point to nodules on the lung surface. Scale bar = 1 cm. (b) Transilluminated lungs from a mouse challenged with SeV but not treated with O/P, as in (a). Arrowheads point to nodules in the lung interior. Scale bar = 1 cm. (c) Enumeration of nodules in the left lungs of mice treated with O/P and challenged with SeV as in (a) (bars indicate mean ± SEM; **P < .01 for [SeV+, O/P+] versus [SeV+, O/P−] by Student's t test; N = 4–5 in a single experiment). (d) Section of the lung of a mouse challenged with SeV but not treated with O/P, stained with H&E. Arrowheads point to nodules. Scale bar = 0.5 mm (N = 4 mice, d–f). (e) High magnification image of a nodule from a mouse as in (d), with closed arrowheads pointing to eosinophilic crystals, open arrowheads pointing to eosinophils and arrows pointing to foamy macrophages. Scale bar = 30 μm. (f) Image of a nodule from a mouse as in (d), but with lungs frozen and stained with Sudan black to show lipids within macrophages. Scale bar = 50 μm. (g) Section of the lung of a mouse challenged with SeV but not treated with O/P, fixed by immersion in methacarn and stained with PAFS. Closed arrowhead points to abundant intracellular mucin, arrow points to lumenal mucus occlusion, and open arrowhead points to mucus in the alveolar region. A = airway, V = vessel. Scale bar = 100 μm. (h) The area of lumenal mucus of mice treated or not with O/P, then challenged or not with SeV and then fixed and stained as in (g), with left lungs sectioned at fixed intervals using a precision cutting tool (bars indicate mean ± SEM; **P < .01 for [SeV+, O/P+] versus [SeV+, O/P−] by Mann–Whitney U test; N = 13–15 mice per group in a single experiment). (i–l) Alveolar region of a mouse challenged with SeV but not treated with O/P, stained with antibodies against (i) club cell specific protein (CCSP) or (j) acetylated tubulin (both brown) and counterstained with H&E (blue). A = airway lumen. Primary antibodies against (k) club cell specific protein or (l) acetylated tubulin were omitted to assess the specificity of antibody staining. Scale bar in all four images = 50 μm (N = 4 mice)