Background: We aimed to study the participation of neurogenic mechanisms in nasal allergic inflammation by assessing the effect of neurogenic stimulation on the secretory and cellular responses of nasal mucosa in patients with allergic rhinitis.
Methods: A group of patients suffering from seasonal allergic rhinitis was challenged intranasally with incremental doses of capsaicin (0.3, 3, 12 μg) during and after the pollen season. Clinical symptoms after provocations were monitored, and unilateral nasal lavages were obtained. The nasal lavage fluid (NAL) was assayed for concentration of total protein, albumin, lactoferrin, and number of leukocytes, following by differential count.
Results: Capsaicin challenge during the pollen season produced greater congestion (P<0.01) and rhinorrhea (P<0.05) than after the season. The intensity of burning sensation (pain) was similar on both occasions. Capsaicin failed to increase albumin content in NAL both during and after the season. Total protein was increased only after the highest dose of capsaicin (P<0.03) after the season. The number of eosinophils in basal lavages was higher during the season. During the season, the total number of leukocytes at least doubled in 7/12 patients and the percentage of eosinophils increased in 6/12 patients after the capsaicin challenge.
Conclusions: Our study demonstrated that during the symptomatic period the nasal mucosa of allergic patients is more susceptible to neurogenic stimulation, showing enhanced secretory and inflammatory (cellular) responses.