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 quan titative aspects of allergic responses because the precise amount of r elevant allergen for each patient is unknown. Objective: We applied is olated IgE-binding components (major allergens) in the technique of br onchial allergen challenge to determine the role of patient characteri stics in the early asthmatic response (EAR), Methods: In 30 patients w ith 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 bro nchial responsiveness to allergen (the cumulated dose of allergen caus ing a 20% fall in FEV1 [PD(20)allergen]) was related to the degree of nonspecific bronchial responsiveness (the concentration of histamine c ausing a 20% fall in FEV1 [PC(20)histamine]) and the level of specific IgE or allergen thresholds as found in skin tests and basophil histam ine release assays. Results: Twenty-seven patients with an immediate r esponse during allergen and histamine challenges (Delta FEV1, greater than or equal to 20%) were analyzed. In these patients, a strong corre lation 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 t he 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; intrac utaneous test, r = 0.49 and p = 0.01) or basophil histamine release as says (r = 0.37, p = 0.08). Moreover, no significant contribution of th ese indices of IgE-mediated hypersensitivity to the prediction of PD(2 0)allergen by multilinear regression models with PC(20)histamine was f ound. Conclusion: In asthmatic patients allergic to house dust mites t he degree of nonspecific bronchial hyperresponsiveness is the main det erminant of early-phase bronchial responsiveness to allergen, In these patients the degree of allergic sensitivity does not contribute to th e prediction of the EAR after allergen inhalation.