Mast cell mediator release following endobronchial challenge with adenosine 5'-monophosphate in asthmatic subjects

Mediator release from activated mast cells is also likely to take place in the asthmatic airways in vivo during adenosine-induced bronchoconstriction. To test this hypothesis, we evaluated mast cell mediator release directly into the airways of 9 asthmatic subjects after endobronchial challenge with adenosine by bronchoalveolar lavage (BAL). The mediators measured were histamine, tryptase, and PGD2. When compared to the saline-challenged segment, the response to AMP instillation was characterized by a prompt reduction in airway calibre paralleled by a significant 4.2-fold increase in PGD2 levels in the BAL fluid (p = 0.004). There were also increases in median histamine (from 200.1 to 433.6 pg/mL) and tryptase levels (from 0.31 to 0.46 ng/mL) recovered after AMP challenge, although they were not significant. These findings support the view that acute bronchospastic response to AMP in asthmatic airways is paralleled by the local release of mast cells derived products, particularly PGD2.