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Airway eosinophilic inflammation and bronchial hyperresponsiveness after allergen inhalation challenge in asthma.

Abstract：

:Allergen exposure in atopic asthmatic patients is associated with recruitment and activation of eosinophils in the airways. Once activated, eosinophils release toxic products, including the eosinophil cationic protein (ECP), able to damage bronchial structures and to increase bronchial hyperresponsiveness. With this background, the present study was designed to evaluate whether ECP levels in bronchoalveolar lavage (BAL) fluid could reflect, better than BAL eosinophil counts, the cellular activation that follows allergen exposure in atopic asthmatics. Twenty-two atopic patients attended the laboratory on two separate days. On the 1st day, they underwent methacholine (MCh) inhalation challenge to detect the degree of nonspecific bronchial hyperresponsiveness. On the 2nd day, they underwent fiberoptic bronchoscopy and BAL, at baseline or 4-6 h after allergen inhalation challenge. In this latter patient group, MCh challenge was repeated 3-5 h after allergen challenge, 1 h before fiberoptic bronchoscopy. The analysis of the mean baseline FEV1 values and the degree of bronchial reactivity to MCh (MCh Pd20) on the 1st study day did not demonstrate differences between the two patient groups (p > 0.1, each comparison). In addition, in the allergen-challenged group, MCh Pd20 was decreased significantly after allergen challenge (151.4 micrograms/ml and 67.6 micrograms/ml, respectively, before and after challenge; p < 0.05). Evaluation of the different BAL cell types demonstrated that the proportions of eosinophils and epithelial cells were increased significantly in the allergen-challenged group compared with the group evaluated at baseline (p < 0.01 and p < 0.05, respectively). Moreover, ECP levels, corrected by the correspondent albumin levels (ECP/Alb), were higher in the allergen-challenged group compared with the group evaluated at baseline (p < 0.05). In addition, although a positive correlation was demonstrated between BAL eosinophil percentages and ECP/Alb values (r = 0.72, p < 0.05) in the group evaluated at baseline, no links were found between these parameters in the allergen-challenged group (p > 0.1). However, in this latter group, a weak positive correlation was demonstrated between eosinophil percentages and delta Mch, i.e., the increased non-specific bronchial reactivity, which is observed after allergen challenge (r = 0.55; p < 0.05). Thus, in stable asthmatic patients an ongoing activation of eosinophils parallels their migration, but this eosinophilic inflammation is not strictly related to bronchial reactivity to Mch. By contrast, after allergen inhalation challenge, eosinophil recruitment and activation seem to follow different temporal kinetics, and eosinophilic inflammation may be partially associated with the degree of airway hyperresponsiveness.

journal_name

Lung

journal_title

Lung

authors

Oddera S,Silvestri M,Penna R,Galeazzi G,Crimi E,Rossi GA

doi

10.1007/pl00007606

subject

Has Abstract

pub_date

1998-01-01 00:00:00

pages

237-47

issue

eissn

0341-2040

issn

1432-1750

journal_volume

176

pub_type

杂志文章

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Airway eosinophilic inflammation and bronchial hyperresponsiveness after allergen inhalation challenge in asthma.