Relationship between cutaneous allergen response and airway allergen-induced eosinophilia.

Background: Determinants of changes in airway caliber after allergen challenge include nonallergic airway responsiveness, immune response and dose of allergen given. However, determinants of the airway inflammatory response to allergens remain to be determined.

Aim: To assess the relationship between skin reactivity to airborne allergens and lower airway eosinophilic response to allergen exposure in asthma and allergic rhinitis.

Methods: Forty-two subjects with mild allergic asthma (mean age 24 years) and 14 nonasthmatic subjects with allergic rhinitis (mean age 25 years) had allergen skin prick tests and titration with the allergen chosen for subsequent challenge. On a second visit, 31 asthmatic subjects had a conventional challenge while 11 asthmatic subjects and all rhinitic subjects had a low-dose allergen challenge over four subsequent days. Induced sputum samples were obtained at 6 and 24 h after the conventional challenge and at days 2 and 4 of the low-dose challenge.

Results: In the asthmatic group, there was a weak correlation between wheal diameter induced by the concentration used for challenge and increase in eosinophils 6 h postconventional challenge (r = 0.372, P = 0.05), but no correlation was observed following the low-dose challenge. Rhinitic subjects showed a correlation between wheal diameter with the allergen dose used for bronchoprovocation and increase in eosinophils at day 2 of low dose (r = 0.608, P = 0.02).

Conclusion: This study suggests that immediate immune responsiveness to allergen, assessed by the magnitude of the skin response, is a significant determinant of allergen-induced airway eosinophilia and can help to predict the airway inflammatory response.