Study objective: To determine the effect of exposure to cigarette smoke on the elastolytic activity of guinea pigs' alveolar macrophages (AMs), and to compare elastolytic activity of AMs obtained by BAL with that of lung macrophages (LMs) obtained from minced lung tissue.
Methods: AMs were obtained by BAL from seven adult guinea pigs exposed to cigarette smoke for 5 d/wk during 6 weeks, as well as from age-matched control guinea pigs. From each animal, one lung was used to obtain LMs by mincing and teasing the lung, followed by enzymatic digestion and isolation of mononuclear cells by Hypaque-Ficoll separation. The other lung was inflated and fixed to quantitate emphysema by the destructive index (DI). Elastolytic activity (microgram of elastin degraded by 106 macrophages) was determined at 24, 48, and 72 h, by culturing AMs and LMs (1x106 cells in 1 mL of medium) in 3H-elastin-coated wells.
Results: In animals exposed to cigarette smoke, the total number of BAL cells (8.6±2.1x106) and DI (21.8±8.1) were significantly higher than in nonexposed animals (6.4±1.8x106, p<0.05 for cells, and 12.1±4.1, p<0.01 for DI). Elastolytic activity of AMs from smoke-exposed guinea pigs was significantly higher at 24, 48, and 72 h than elastolytic activity of AMs from control animals (19.0±9.4 vs 10.0±5.3, p<0.05 at 72 h). Likewise, elastolytic activity of LMs was significantly higher in exposed than nonexposed guinea pigs (11.8±7.7 vs 7.4±5.0 at 72 h, p<0.05). Elastolytic activity of LMs was not significantly different from elastolytic activity of AMs, both in exposed guinea pigs (11.8±7.7 vs 19.0±9.4 at 72 h) and nonexposed animals (7.4±5.0 vs 10.0±5.3 at 72 h).
Conclusions: These results indicate that elastolytic activity of both AMs and LMs of guinea pigs increases significantly after exposure to cigarette smoke and that AMs and LMs have similar elastolytic activities.