Objective and design: This study examined whether bradykinin and neurokinin A activate human pulmonary mast cells retrieved by bronchoalveolar lavage (BAL).
Subjects: BAL samples were obtained at routine bronchoscopy from 14 unpreselected patients.
Methods: Histamine release experiments were performed using substance P, neurokinin A, bradykinin (peptides 25 and 50 microM), compound 48/80 (0.75-10 micrograms/ml) and A23187 (1 microM). Statistical analyses were performed using the paired Student's t-test and Pearson's linear correlation coefficient.
Results: Compound 48/80 induced release was significantly lower than that induced by the other secretagogues (p < 0.05). Neurokinin A and bradykinin induced release correlated significantly with substance P induced release (p < 0.01), suggesting similar mechanisms of action. No correlations were observed between neurokinin A or bradykinin-induced release and the non-peptide stimuli studied.
Conclusions: The mechanism of neurokinin A- and bradykinin-induced bronchoconstriction is not yet clear but our data suggest an indirect effect mediated by mast cell degranulation.