Epithelial shedding is associated with nasal reactions to cold, dry air.

Background: Cold, dry air (CDA) can cause symptoms of rhinitis and obstructive airway responses. The pathophysiology of these reactions is not understood. One hypothesis is that the respiratory mucosa of individuals with CDA sensitivity cannot compensate for the loss of water that occurs on exposure to the stimulus, leading to epithelial damage. Objective: To test for an association between nasal reactions to CDA and the number of epithelial cells recovered in nasal fluids. Methods: Ten CDA-sensitive subjects received nasal provocations with CDA and warm, moist air; 10 CDA-insensitive subjects received CDA; and 10 subjects with allergic rhinitis received allergen and diluent challenges. Nasal lavage cytology was performed at baseline and after the challenge. Symptoms were recorded and histamine, [³H]-N-α-tosyl-L-arginine methyl ester-esterase activity, tryptase, and albumin were assayed in nasal lavages. Results: A 6-fold increase in nasal lavage epithelial cells was found in the CDA-sensitive group after CDA (P < .01), but not after warm, moist air. No changes were observed in the CDA-insensitive group, or after allergen or diluent in allergic rhinitis. Conclusion: Epithelial cell shedding accompanies clinical responses to CDA in the human nose. This supports the hypothesis that the airway mucosa of CDA-sensitive individuals cannot compensate for the water loss that occurs under extreme conditions leading to epithelial damage. Clinical implications: A defect in mucosal water homeostasis may need to be considered in individuals who get excessive nasal symptoms when exposed to cold and dry, windy environment. [Copyright &y& Elsevier]