Chronic bronchitis is associated with airways obstruction and inflammation. In order to determine whether aerosolized beclomethasone can modulate airway inflammation and diminish airway obstruction, subjects with chronic bronchitis performed spirometry and underwent bronchoalveolar lavage (BAL) before and after receiving 6 wk of therapy (five puffs four times a day) with either aerosolized beclomethasone (n = 20) or placebo (n = 10) in a double-blinded, randomized fashion. All subjects received aerosolized albuterol before each use of the study medications. Before BAL, the airways were visually assessed for the appearance of inflammation and assigned a score, the bronchitis index. BAL was performed by instilling five 20-ml aliquots of saline into each of three sites and pooling and separately analyzing the returns from the first aliquots to yield a "bronchial sample." The bronchial lavages were repeated in an additional three sites to increase the volume of fluid available for analysis. The fluid was prepared for cytologic examination by cytocentrifugation. Albumin (as a measure of epithelium permeability) and lactoferrin and lysozyme (as measures of serous cell activity) were measured in unconcentrated BAL fluid by enzyme-linked immunosorbent assay, and concentrations in epithelial lining fluid were estimated using urea as an internal marker for dilution. After treatment, the beclomethasone group, but not the placebo group, showed improvement in FVC (p = 0.02), FEV1 (p = 0.002), and 25 to 75% forced expiratory flow (p = 0.006). Associated with the improvement in spirometry, the bronchitis index fell (13.5 +/- 1.0 versus 10.75 +/- 1.1, p = 0.02) in the beclomethasone-treated group, but not the placebo-treated group.(ABSTRACT TRUNCATED AT 250 WORDS)