Relationship between nasal hyperreactivity, mediators and eosinophils in patients with perennial allergic rhinitis and controls.

Background: In perennial allergic rhinitis, patients are almost daily exposed to aeroallergens. This ongoing allergic reaction results in increased sensitivity to allergens and non-specific stimuli. It is generally known that inflammatory cells and mediators are involved in the pathogenesis of the allergic reaction.
Objectives: To study the relationship between nasal hyperreactivity and nasal inflammation during natural allergen exposure.
Methods: In 48 patients with perennial allergic rhinitis and in 11 volunteers a nasal brush, a nasal lavage and a histamine challenge were performed. Nasal inflammation was estimated by the number of eosinophils, levels of albumin, tryptase, prostaglandin D2 (PGD2), eosinophil cationic protein (ECP) and leukotriene C4/D4/E4 (LTC4/D4/E4).
Results: In contrast to PGD2 and tryptase, eosinophils (1.9 vs 0%, P = 0.0023), LTC4/ D4/E4 (17.51 vs 1.43 pg/mL, P < 0.0001) and albumin (8.61 vs 2.37 mg/mL, P = 0.0008) were significantly increased in rhinitis patients as compared with controls. Patients also showed increased responses to nasal histamine challenge assessed using a composite symptom score (21.5 vs 4 points, P < 0.0001). The nasal response to histamine was weakly correlated with the total number of eosinophils in the cytospin (correlation coefficient r = 0.38, P = 0.009).
Conclusion: Nasal hyperreactivity is correlated with the percentage of eosinophils in patients with perennial rhinitis. The patients' mediator profiles suggest that eosinophils are important in the ongoing allergic reaction and nasal hyperreactivity.