Bronchial hyperresponsiveness in a patient with systemic mastocytosis

In order to investigate the possible involvement of airway mast cells in bronchial hyperresponsiveness (BHR), we examined whether a patient with systemic mastocytosis would demonstrate BHR against ultrasonically nebulized distilled water (UNDW) and histamine inhalation challenge. A 56-year-old man with systemic mastocytosis underwent both UNDW and histamine inhalation challenge. We also evaluated the effect of beclomethasone dipropionate inhalation (BDI) treatment on the histamine inhalation challenge. The results showed that UNDW inhalation caused no changes in forced expiratory volume in 1 s (FEV1) for this patient. The provocative dose causing a 20% fall (PC20) in FEV1 in the histamine inhalation challenge was 625 microg/mL. After BDI treatment for 8 weeks, the histamine PC20 was still 625 microg/mL. These data suggest that UNDW-induced bronchoconstriction may be independent of airway mast cells and that the mechanism of histamine-induced bronchoconstriction in systemic mastocytosis may be independent of airway inflammation, which is often present in asthmatics.