The ratio of 50 kd/46 kd VASP in epithelial cells increased 1 to 2 weeks after Ag challenge but not significantly (p = 0.12). Asthmatic epithelial cells have a significantly lower ratio of 50 kd/46 kd VASP than do nonatopic, nonasthmatic epithelial cells (eight patients) [p < 0.001]. After inhaled β2-agonist use, the 50 kd/46 kd VASP ratio significantly increased in both control and challenged segment epithelium of asthmatic patients (p = 0.003), but not after placebo use (p = 0.79). Moreover, significantly increased numbers of Alcian blue-stained, mucin-secreting epithelial cells were observed in the BAL fluid of unchallenged segments of asthmatic patients receiving β2-agonist therapy, but not in that of patients receiving placebo (p < 0.001 for group; p = 0.014 for day; and p = 0.004 for group vs day interaction). Accordingly, significantly increased total numbers of epithelial cells in BAL fluid (ie, Alcian blue-stained, ciliated, and other columnar epithelial cells) were observed for β2-agonist agents but not placebo (p < 0.001 for group; and p = 0.014 for group vs day interaction).