Figure 3 Alveolar Macrophage Chemiluminescence. (A) Total alveolar macrophage chemiluminescence and (B) 1400W-sensitive alveolar macrophage chemiluminescence was determined at 1, 7, 14, and 28 days postexposure. For each postexposure 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.