FIG. 3.

Representative photomicrographs of vaccine-boosted mice following aerosol infection with M. tuberculosis. All plates were stained with hematoxylin and eosin. (A) Lung adjacent to a bronchiole (arrowhead) from a mouse from the BCG vaccination group. Alveolar septa containing epithelioid macrophages and infiltrates of neutrophils, often forming small aggregates, are evident (arrows). (B) Lung adjacent to a bronchiole (arrowhead) from a mouse from the BCG-Ag85 vaccination group. The alveolar septa show evidence of influx by epithelioid macrophages, whereas neutrophils are scattered and rare (arrows). (C) Higher magnification of lung from a mouse from the BCG vaccination group. Arrows depict an aggregate or pocket of neutrophils within an alveolar septa. (D) Higher magnification of lung from a mouse from the BCG-Ag85 vaccination group. The septa are thickened by an influx of macrophages. Neutrophils are rare; the arrow indicates a solitary neutrophil. Bars, 10 μm.