Figure 1 Bronchoalveolar lavage alveolar macrophages and polymorphonuclear leukocytes. (A) Bronchoalveolar lavage macrophages and (B) polymorphonuclear leukocyte numbers were determined at 1, 7, 14, and 28 days post-IT exposure. For each post-IT exposure time, an "a" indicates a significant difference versus saline control group, and a "b" indicates a significant difference versus silica-exposed group. Values represent mean ± SE, n = 7–8 per group. Significance was set at p 0.05.