Bronchial allergen challenge with isolated major allergens of Dermatophagoides pteronyssinus: The role of patient characteristics in the early asthmatic response

Background: The use of allergen extracts will hamper studies into quantitative aspects of allergic responses because the precise amount of relevant allergen for each patient is unknown. Objective: We applied isolated IgE-binding components (major allergens) in the technique of bronchial allergen challenge to determine the role of patient characteristics in the early asthmatic response (EAR). Methods: In 30 patients with mild-to-moderate asthma, the EAR was investigated after inhalation of an isolated major allergen of Dermatophagoides pteronyssinus (i.e., Der p 1 [ n = 16] or Der p 2 [ n = 14]). The degree of early-phase bronchial responsiveness to allergen (the cumulated dose of allergen causing a 20% fall in FEV 1 [PD 20allergen]) was related to the degree of nonspecific bronchial responsiveness (the concentration of histamine causing a 20% fall in FEV 1 [PC 20histamine]) and the level of specific IgE or allergen thresholds as found in skin tests and basophil histamine release assays. Results: Twenty-seven patients with an immediate response during allergen and histamine challenges (ΔFEV 1 , ≥20%) were analyzed. In these patients, a strong correlation was found between PD 20 allergen and PC 20 histamine ( r = 0.81, p < 0.001). Weak correlations were found between PD 20 allergen and the level of specific IgE ( r = –0.36, p = 0.07) or allergen thresholds as found in skin tests (skin prick test, r = 0.36 and p = 0.07; intracutaneous test, r = 0.49 and p = 0.01) or basophil histamine release assays ( r = 0.37, p = 0.08). Moreover, no significant contribution of these indices of IgE-mediated hypersensitivity to the prediction of PD 20 allergen by multilinear regression models with PC 20 histamine was found. Conclusion: In asthmatic patients allergic to house dust mites the degree of nonspecific bronchial hyperresponsiveness is the main determinant of early-phase bronchial responsiveness to allergen. In these patients the degree of allergic sensitivity does not contribute to the prediction of the EAR after allergen inhalation. (J Allergy Clin Immunol 1998;102:24-31.)