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Airway responsiveness to mannitol 24 h after allergen challenge in atopic asthmatics
Author(s) -
Davis B. E.,
Amakye D. O.,
Cockcroft D. W.
Publication year - 2015
Publication title -
allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.363
H-Index - 173
eISSN - 1398-9995
pISSN - 0105-4538
DOI - 10.1111/all.12601
Subject(s) - methacholine , allergen , medicine , inhalation , mannitol , airway , asthma , immunology , allergy , exhaled nitric oxide , provocation test , anesthesia , bronchoconstriction , respiratory disease , lung , chemistry , pathology , alternative medicine , organic chemistry
Background Airway responsiveness to indirect stimuli correlates positively with airway inflammation. In atopic asthmatics, allergen inhalation is associated with an influx of inflammatory cells and increased responsiveness to the direct‐acting stimuli methacholine at 3 and 24 h after exposure. We have shown mannitol responsiveness decreases 3 h after allergen inhalation. The current investigation assessed mannitol responsiveness 24 h after allergen challenge. Methods Eleven mild atopic asthmatics completed allergen challenges on two separate occasions. In random order, methacholine or mannitol challenges were performed 24 h pre‐ and post–allergen challenge. Levels of fractional exhaled nitric oxide were also measured. Results Allergen challenge increased airway responsiveness to methacholine 24 h postchallenge; the geometric mean (95% CI) methacholine PC 20 decreased from 5.9 mg/ml (1.8–19.4) to 2.2 mg/ml (0.81–5.89); P = 0.01. This coincided with a significant increase ( P = 0.02) in FeNO levels. Conversely, allergen challenge decreased airway responsiveness to mannitol; geometric mean (95% CI) dose–response ratio was significantly higher after allergen exposure (57 mg/% FEV 1 fall [27–121] to 147 mg/% FEV 1 fall [57–379]; P = 0.03), and FeNO levels were not significantly increased ( P = 0.054). Conclusion Allergen‐induced changes in airway responsiveness to direct and indirect stimuli are markedly different. The loss in responsiveness to mannitol is likely not explainable by a refractory state. The effect(s) of allergen exposure on airway responsiveness to indirect‐acting stimuli require further investigation.