RESUMO
BACKGROUND: Conflicting results have been reported in studies of predictive factors for airway responsiveness to allergens during bronchial challenges. OBJECTIVE: The aim of this study was to assess determinants of airway responsiveness to 3 different allergens during standardized bronchial challenges. METHODS: Data were collected from asthmatic patients who participated in allergen challenge trials between 2000 and 2006 (cat, n = 37; house dust mite [HDM], n = 35; grass pollen, n = 27). PD20 (provocative dose causing a 20% fall in forced expiratory volume in the first second) methacholine, PD20 allergen, allergen skin test endpoint, allergen-specific immunoglobulin (Ig) E levels, and late asthmatic response were analyzed for each allergen group. RESULTS: During the early asthmatic response, a significant relationship was found between PD20 allergen and PD20 methacholine (P < .01 for cat, HDM, and grass pollen), as well as between PD20 allergen and allergen-specific IgE levels (P < .05 for cat and HDM). No relationship was observed between PD20 allergen and allergen skin test endpoint (P > .05). Late asthmatic response was significantly more frequent after HDM challenge than after cat or grass pollen challenges (57.1% vs16.2% and 33.3%, P < .01). Dual responders during HDM challenges had significantly higher allergen-specific IgE levels (P < .05) and higher nonallergic airway responsiveness (P < .05). CONCLUSION: Nonallergic airway hyperresponsiveness and allergen-specific IgE levels were the main determinants of early and late asthmatic responses. HDM challenges were the most interesting model with regard to the occurrence of late asthmatic response. In contrast to previous publications and to the official statement on standardized challenge testing with sensitizing stimuli, skin sensitivity appears to be a poor predictor of the early asthmatic response.