Bronchoalveolar lavage (BAL) was performed in eight patients with allergic bronchopulmonary aspergillosis (ABPA) at a time when chest roentgeongraphy did not reveal an infiltrate, and respiratory status was stable. BAL was tolerated well by all patients with only one patient experiencing mild wheezing. BAL fluid recovery averaged 40%, and total cells/lavage were 22.3 x 10(6) (range 3.5 to 49.5 x 10(6)). Cell viability, as determined by trypan blue exclusion, averaged 48% (range 34% to 60%). Mean values for cellular elements were macrophages, 62%; epithelial cells, 12%; lymphocytes, 16%; neutrophils (PMN), 4%; and eosinophils, 6%. Isotypic antibodies to Aspergillus fumigatus (Af) in BAL and serum were detected by an amplified indirect ELISA. Antibodies to Af in BAL expressed as optical density/albumin (milligrams per milliliter) were compared to BAL from six nonatopic patients. IgE-Af and IgA-Af in BAL were elevated in patients with ABPA compared with six nonatopic patients. The ratios of Ig-Af in BAL to peripheral blood in patients with ABPA were 48 (range 18 to 75) for IgE-Af, 96 (range 37 to 159) for IgA-Af, and 0.94 (range 0.24 to 1.40) for IgG-Af, suggesting local production of IgE-Af and IgA-Af in the bronchoalveolar compartment. Total serum IgE correlated directly with IgE-Af in BAL (rs = 0.67; p less than 0.02). However, the ratio of total BAL IgE/albumin divided by total serum IgE/albumin was 0.93 +/- 0.94, suggesting that the bronchoalveolar compartment is not the source of the significant elevations in total serum IgE in ABPA.