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Bronchial responsiveness is not always increased after allergen challenge
A J Ward1, M G McKenniff, J M Evans
1Department of Thoracic Medicine, King's College School of Medicine and Dentistry, London, U.K.
Respiratory Medicine
|July 1, 1994
Summary
Allergen challenge in mild asthmatics did not significantly increase bronchial responsiveness, even in those with a late asthmatic response. This suggests that high baseline responsiveness may limit further increases after allergen exposure.
Area of Science:
- Allergy and Immunology
- Respiratory Medicine
- Pulmonary Physiology
Background:
- Increased bronchial responsiveness is observed after allergen challenge (AC), potentially linked to the late asthmatic response (LAR).
- Understanding this relationship is crucial for managing allergic asthma and predicting treatment outcomes.
Purpose of the Study:
- To investigate the effect of house dust mite allergen challenge (HDM) on bronchial responsiveness in mild asthmatics with a known late asthmatic response (LAR).
- To determine if the magnitude of LAR correlates with changes in bronchial responsiveness.
Main Methods:
- Twenty mild asthmatics with a confirmed LAR to HDM were studied.
- Bronchial responsiveness was assessed using methacholine provocation concentration (PC20 FEV1) before and 24 hours after HDM inhalation.
- Correlation analysis was performed between changes in PC20 FEV1, LAR magnitude, and FEV1 changes.
Main Results:
- No significant change in bronchial responsiveness (log PC20) was observed 24 hours after HDM challenge (P = 0.38).
- The change in PC20 FEV1 did not correlate with the size of the LAR (r = -0.33; P > 0.05).
- A significant correlation was found between the change in PC20 FEV1 and the absolute change in FEV1 at 24 hours (r = 0.67; P < 0.01).
Conclusions:
- In mild asthmatics with a high baseline bronchial responsiveness, allergen challenge may not lead to a significant increase in responsiveness.
- The study suggests that allergen exposure in individuals with late asthmatic responses does not invariably increase non-specific bronchial hyperresponsiveness.