Influence of allergen avoidance on the eosinophil phase of airway inflammation in children with allergic asthma

BACKGROUND: Exposure to relevant allergens causes an increase in bronchial hyperresponsiveness, as well as an inflammatory reaction at the site of the bronchial mucosa in patients with asthma. OBJECTIVE: The purpose of this study was to determine whether antigen avoidance can exert an antiinflammatory effect on the eosinophil phase of airway inflammation in children with asthma. METHODS: The level of bronchial hyperreactivity and the percentage of eosinophils in sputum samples obtained by inhalation of hypertonic saline solution, were evaluated in a group of asthmatic children allergic to house dust mite before and after a period of antigen avoidance in an Alpine environment (1756 m). RESULTS: At the end of the avoidance period PC20 increased from a median value (lower and upper quartile: Q1, Q3) of 1.17 (0.74, 4.75) to 3.5 (1.18, 8.87) mg/ml (p = 0.02), and eosinophil percentage in the sputum decreased from a median value (Q1, Q3) of 14.02 (3.34, 28.24) to 2.08 (0, 7.4) (p less than 0.01). CONCLUSION: A 3-month period of antigen avoidance can significantly reduce the eosinophil phase of airway inflammation, along with bronchial hyperresponsiveness, in patients with asthma