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Clin Exp Allergy. 2015 Nov;45(11):1647-53. doi: 10.1111/cea.12587.

Allergen-induced early and late asthmatic responses to inhaled seasonal and perennial allergens.

Author information

1
Institut universitaire de cardiologie et de pneumologie de Québec (IUCPQ), Québec, Québec, Canada.
2
Department of Medicine, McMaster University Medical Center, Hamilton, Ontario, Canada.
3
Division of Respirology, Critical Care and Sleep Medicine, Royal University Hospital, Saskatoon, Saskatchewan, Canada.

Abstract

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 ABPs, all performed with a common standardized methodology. Patients were either challenged with house dust mites (HDMs), animals or pollens allergens. EAR was defined as a ≥ 20% fall in forced expiratory volume in 1 s (FEV1 ) < 3 h following ABP and LAR as a ≥ 15% fall in FEV1 between 3 and 7 h post-ABP. The ratio of EAR % fall in FEV1 /LAR % fall in FEV1 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 PC20 , a more marked fall in FEV1 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.

KEYWORDS:

airway hyperresponsiveness; airway inflammation; allergen bronchoprovocation tests; allergens; asthma; late asthmatic responses

PMID:
26115509
DOI:
10.1111/cea.12587
[Indexed for MEDLINE]

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