To determine if atopic subjects without asthma naturally exposed to antigens to which they are sensitized demonstrate evidence of lower airway inflammation, we studied 10 subjects with recurrent seasonal allergic rhinitis to pollens. Each subject had a monthly methacholine challenge and two bronchoalveolar lavages (BAL), one during symptoms of allergic rhinitis and one out of season. The percentage of macrophages, lymphocytes, neutrophils, eosinophils, and mast cells in the lavage fluid were determined on Diff-Quik, nonspecific esterase, or toluidine blue-stained cytocentrifuge preparations. The total number of cells recovered on BAL was 23.2 +/- 3.5 X 10(6) (mean +/- SEM) (13.3 +/- 2.3 X 10(4) cells per milliliter) in season, during symptoms of allergic rhinitis, and 33.8 +/- 7.4 X 10(6) (15.2 +/- 3.1 X 10(4) cells per milliliter) out of season (p greater than 0.05). BAL cell-differential counts (percent) in/out season were similar for macrophages (89.0/84.6), lymphocytes (9.1/12.8), neutrophils (1.3/2.1), eosinophils (0.5/0.5), epithelial cells (0.37/0.46), and mast cells (0.0008/0.0013). Blood eosinophil counts, taken, respectively, in and out of season, were 135.5 +/- 26.8 X 10(6)/L and 102.8 +/- 20.6 X 10(6)/L (p greater than 0.05). Although overall airway responsiveness increased slightly during the pollen season, it did not reach statistical significance (geometric mean of provocative concentration causing a 20% fall in FEV1 [milligrams per milliliter], 98.8 during antigenic exposure compared to 121.4 out of season) (p greater than 0.05. These observations suggest that in subjects without asthma, no changes in cell differential are detected on BAL at the time of maximal symptoms of allergic rhinitis.