Effects of allergen exposure-avoidance on inflammation in asthmatic children

Inflammation of the airways has long been known to be the classic pathologic feature of asthmatics who have died in status asthmaticus (1, 2). However, it has recently been appreciated, from studies of bronchial lavage and bronchial biopsies, that inflammatory changes are present in even mildly symptomatic adult patients (3). Experimental evidence has linked the induction of bronchial hyperresponsiveness (BHR) to the presence of inflammation (4-7). The recognition of allergic airways inflammation, as a cause of both transient and persistent airway hyperresponsiveness, has led to increased appreciation of importance of atopy in the pathogenesis of asthma (4-8). Recently, it has been shown that eosinophil counts in lavage fluid are correlated with histamine reactivity in children (9) as well as in adults (3). Furthermore, ultrastructural examination of the airways of two asthmatic children undergoing open lung biopsy during clinical remission showed features similar to lung tissue from two children who had died in status asthmaticus with the exception of a larger number of submucosal eosinophils and more extensivedenudation ofthe epithelium in fatal asthma (10). Evidence from these findings suggest that airways-inflammation may play a role also in asthmatic children. This hypothesis can be further supported by studies which have shown that allergen avoidance can improve BHR and asthma symptoms both in adults (11-12) and children (13-15) with asthma. Because of the importance of better understanding the correlation of allergen exposure with BHR and inflammation we evaluated changes in BHR and serum markers of inflammation when allergic asthmatic children sensitive to house dust mites moved from an environment rich in allergens (sea level) to an environment free from mites at a high altitude (Istituto Pi0 XII, Misurina 1756111) (16-17) and back again to sea level. The migration of asthmatic children from sea level to the alpine environment and back again, offers a natural allergen exposureavoidance-exposure challenge model.