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Allergen‐induced early and late asthmatic responses to inhaled seasonal and perennial allergens
Author(s) -
Boulet L.P.,
Gauvreau G.,
Boulay M.E.,
O'Byrne P.M.,
Cockcroft D. W.
Publication year - 2015
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1111/cea.12587
Subject(s) - medicine , allergen , asthma , eosinophil , immunology , allergy , aeroallergen
Summary Background The allergen bronchoprovocation ( ABP ) test is a validated model to study asthma pathophysiology and response to treatments. The inhibitory effect of agents on the allergen‐induced late asthmatic response ( LAR ) is a predictor of their efficacy in asthma treatment. However, it is difficult to predict the magnitude of a LAR , which may vary according to immune responsiveness and the type of allergen used for ABP . Aim To determine the relationship between the magnitudes of early asthmatic response ( EAR ) and LAR in mild asthmatic subjects according to the type of allergen inhaled and its determinants. Methods This is a retrospective analysis of a large database of ABP s, all performed with a common standardized methodology. Patients were either challenged with house dust mites ( HDM s), animals or pollens allergens. EAR was defined as a ≥ 20% fall in forced expiratory volume in 1 s ( FEV 1 ) < 3 h following ABP and LAR as a ≥ 15% fall in FEV 1 between 3 and 7 h post‐ ABP . The ratio of EAR % fall in FEV 1 / LAR % fall in FEV 1 was compared between the groups of subjects according to the allergen used for ABP . Results Data from 290 subjects were analysed: 87 had an isolated EAR and 203 had a dual response ( EAR + LAR ). Dual responders had a significantly lower baseline PC 20 , a more marked fall in FEV 1 at EAR , and a trend towards higher baseline sputum eosinophil percentages. The ratio of EAR over LAR was significantly lower in HDM compared with pollen ABP , indicating a larger LAR for a similar EAR . No correlations were observed between the ratio of EAR over LAR and the various parameters recorded in the different groups analysed. Conclusion Different mechanisms may be involved in modulating the magnitude of the LAR , according to the type of allergen. HDM seems to induce a stronger LAR than pollens, animal allergens being intermediary in this regard.