Objective: The aim of this study was to determine whether allergic inflammation induces nasal hyperreactivity to bradykinin by enhancing neuronal responsiveness.
Methods: We compared the response to localized, unilateral nasal challenge with bradykinin in patients with perennial allergic rhinitis and nonallergic subjects, and in patients with seasonal allergic rhinitis challenged in and out of season. Weights of secretions from each nostril were recorded, and levels of albumin and lactoferrin in secretions recovered from each nostril were assayed. Contralateral administration of atropine (0.32 mg) was used to evaluate the role of cholinergic reflexes in nasal hyperresponsiveness to bradykinin.
Results: In patients with symptomatic allergy, bradykinin induced greater symptom scores than in asymptomatic atopic or nonallergic control subjects. Moreover, bradykinin caused sneezing in a majority of patients with symptomatic allergy but in none of the asymptomatic atopic or nonallergic control subjects. Only patients with symptomatic allergy showed dose-dependent bilateral increases in secretion weights and levels of the serous glandular marker, lactoferrin. In contrast, bradykinin induced similar increases in ipsilateral, but not contralateral, levels of albumin in all patient populations. Atropine inhibited contralateral secretion and lactoferrin production (p < 0.05) in patients with symptomatic allergy.
Conclusion: The induction of sneezing and of atropine-inhibitable contralateral glandular secretion demonstrates that allergic inflammation causes nasal hyperreactivity to bradykinin, at least in part, by enhancing neuronal responsiveness.