Atopic cough-like cough hypersensitivity caused by active sensitization with protein fraction of Aspergillus restrictus strain A-17

We examined the sensitivity of the cough reflex to inhaled citric acid in guinea pigs that had been actively sensitized with the protein fraction of Aspergillus restrictus strain A-17. The number of coughs elicited by an aerosol of 5% citric acid was significantly increased in the sensitized group compared to the non-sensitized group. The number of citric-acid-induced coughs in sensitized guinea pigs was dose-dependently and significantly reduced to the level in non-sensitized guinea pigs when animals were pretreated with fexofenadine, a selective histamine H1 receptor antagonist, 60 min before citric acid inhalation. The bronchial responsiveness to inhaled methacholine or histamine in the sensitized group was not significantly heightened compared to the non-sensitized group. These results suggest that active sensitization with the protein fraction of A. restrictus by itself, that is without subsequent allergen challenge, enhances the excitability of cough receptors to tussive stimuli, and the physiologic features of this animal model are consistent with those of atopic cough.