Mediator release after endobronchial antigen challenge in patients with respiratory allergy

Abstract

The aim of the present study was to evaluate the release of some potential mediators of allergic reactions, such as histamine, peptide leukotrienes (LTs), LTB 4 and prostaglandin D 2 (PGD 2), in bronchoalveolar lavage (BAL) fluids from 11 patients with respiratory allergy (eight with bronchial asthma and three with allergic rhinitis), who underwent specific endobronchial challenge. Histamine, peptide LT, and PGD 2 levels in BAL fluids increased significantly after antigen stimulation both in patients with asthma and in patients with rhinitis. By contrast, LTB 4 concentration was always below the limits of detection of the radioimmunoassay. In patients with asthma, histamine concentration increased from 5.3 ± 0.6 ng/ml in lavages obtained before provocation to 20.2 ± 5.8 ng/ml (mean ± SEM; p < 0.04) 5 minutes after bronchoprovocation. Peptide LTs increased from 0.32 ± 0.08 to 0.82 ± 0.21 ng/ml ( p < 0.02) and PGD 2 from 0.06 ± 0.01 ng/ml to 0.36 ± 0.09 ng/ml (p < 0.02). Elevated histamine, peptide LT, and PGD 2 concentrations were also found in the 15-minute postchallenge BAL fluids. Similar results were obtained in patients with rhinitis. Histamine concentration was 3.4 ± 0.6 ng/ml in prechallenge bronchial lavages and 11.3 ± 1.7 ng/ml in postchallenge lavages; peptide LTs increased from 0.13 ± 0.008 ng/ml to 0.73 ± 0.21 ng/ml, and PGD 2 from 0.05 ± 0.01 ng/ml to 0.26 ± 0.06 ng/ml. Histamine, peptide LTs, and PGD 2 were released into bronchial airways after local antigen challenge in all 11 subjects with respiratory allergy, whereas in three normal subjects (not allergic to the antigen used), there was no release of these mediators into BAL fluid above their basal concentrations. These findings, combined with known effects on human airways, suggest that histamine, peptide LTs, and PGD 2 may be important in the pathogenesis of early antigen-induced asthmatic reactions.