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Updated: Jul 8, 2026
Murine Model of Allergen Induced Asthma
Published on: May 14, 2012
Bronchial challenge test in asthmatics sensitized to mites: role of particle size in bronchial response
Anne Casset1, Ashok Purohit, Emile Birba
1Département de Pneumologie, Hôpital Lyautey, Hôpitaux Universitaires de Strasbourg, BP 426, 67091 Strasbourg, France.
Abstract:
Although major house dust mite allergen (Der p 1) is carried mainly on large particles (>10 microm), standard bronchial challenge tests (BCT) use nebulizers that deliver smaller particles (sizes from 1 to 5 microm) and may therefore not reflect actual domestic exposure. The objective of this study was to evaluate the influence of particle size of Dermatophagoides pteronyssinus extract on bronchial response. Specific BCT were performed with different mass median aerodynamic diameters (MMAD): 1.1, 5.6, and 9.7 microm. Each of the 19 mite-sensitized patients underwent mite BCT three times, once with each nebulizer. IL-5 levels were assessed in induced sputum and blood samples. The PD(20) for Der p 1 differed substantially with particle size, with less Der p 1 (11.2 ng) needed to produce a PD(20) with the largest particles (9.7 microm), compared to 18.1 ng for the 5.6 microm particles and 142.5 ng for the 1.1 microm particles (p < 0.0001). Large particles also induced an early phase response significantly more often than small particles (100% vs. 63%). Although the late phase reaction (LPR) frequency was similar with all three particle sizes, lower mean oral corticosteroid doses were needed to treat LPR with the largest particles (23 mg), compared to the smaller particles, with 34 mg for the 5.6 microm particles and 51 mg for the 1.1 microm. The 1.1 microm particles produced a significantly greater increase in IL-5 concentrations in sputum and blood compared to the larger particles. Large particles clearly play a role in the immediate bronchial response in asthmatics sensitized to mites and, therefore, should be included in pharmacological studies in humans.
Insights
House dust mite allergen particle size significantly impacts asthma responses. Larger particles trigger immediate bronchial reactions more effectively, suggesting their importance in clinical studies for mite-sensitized asthma patients.
Area of Science:
- Allergy and Immunology
- Respiratory Medicine
- Pharmacology
Background:
- House dust mite allergen (Der p 1) exposure is a key factor in asthma.
- Standard bronchial challenge tests (BCT) may not accurately mimic real-world exposure due to small particle sizes.
- The influence of allergen particle size on bronchial response requires further investigation.
Purpose of the Study:
- To evaluate the impact of Dermatophagoides pteronyssinus extract particle size on bronchial reactivity in mite-sensitized individuals.
- To compare bronchial responses using different mass median aerodynamic diameters (MMAD).
- To assess the role of particle size in immediate and late-phase asthmatic reactions.
Main Methods:
- Bronchial challenge tests (BCT) were conducted on 19 mite-sensitized patients using Der p 1 extract with MMADs of 1.1, 5.6, and 9.7 microm.
- Bronchial response was measured by the provocative dose causing a 20% fall in FEV1 (PD20).
- Interleukin-5 (IL-5) levels were measured in sputum and blood samples.
Main Results:
- A significantly lower dose of Der p 1 was required to elicit a PD20 with larger particles (9.7 microm) compared to smaller particles (1.1 microm).
- Large particles induced an early-phase asthmatic response more frequently (100%) than small particles (63%).
- Smaller particles (1.1 microm) led to a greater increase in IL-5 levels in sputum and blood.
Conclusions:
- Larger allergen particles play a significant role in the immediate bronchial response in mite-sensitized asthmatics.
- Current BCT methods using small particles may underestimate the clinical impact of mite allergen exposure.
- Future pharmacological studies should incorporate larger particle sizes to better reflect domestic exposure and clinical relevance.
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