ATOPY AND BRONCHIAL HYPERRESPONSIVENESS IN PURE EXTRINSIC CHILDHOOD ASTHMA

Nonspecific bronchial hyperresponsiveness and atopy are considered ris k factors in the development of asthma. Bronchial responsiveness to al lergens could be the most important factor in extrinsic asthma. The tr ial was designed to investigate the role of specific and nonspecific b ronchial responsiveness and atopy in a pure model of extrinsic asthma in children. One hundred and thirty-seven patients with pollen allergy were evaluated. Twenty children with allergy to grass pollen (Lolium perenne) alone, with symptoms only in the grass pollen season, were se lected Their score of symptoms, airway responsiveness to methacholine in and out of season, airway responsiveness to Lolium perenne out of s eason, and total and specific IgE were assessed. Twelve were male and eight female. Mild asthma was observed in 14, and moderate asthma in s ix. Age of onset of symptoms ranged from three to 13 years of age. Sig nificant seasonal increase in airway responsiveness to methacholine wa s found (p = 0.002). Specific bronchial challenge test was positive in all patients. Lolium perenne PD20 ranged from 2.3 to 155.5 inhalation units. An inverse association between age of onset of symptoms and se verity of asthma was shown (p = 0.001). Increase in nonspecific bronch ial responsiveness was related to the appearance of symptoms during th e spring, but it showed no relationship to the severity of symptoms. S everity of asthma during the spring correlated with the intensity of a llergen airway responsiveness (p = 0.02). Levels of total and specific IgE were not related to the degree of specific or nonspecific airway responsiveness. Severity of extrinsic childhood asthma is determined b y bronchial response to allergens. Bronchial hyperresponsiveness to me thacholine during the spring can be the consequence of environmental e xposure to allergens The intensity of airway responsiveness to methach oline has no predictive value in the severity of pure extrinsic childh ood asthma.