Atopy and bronchial hyperresponsiveness in pure extrinsic childhood asthma.

ABSTRACT

Nonspecific bronchial hyperresponsiveness and atopy are considered risk factors in the development of asthma. Bronchial responsiveness to allergens could be the most important factor in extrinsic asthma. The trial was designed to investigate the role of specific and nonspecific bronchial 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 selected. Their score of symptoms, airway responsiveness to methacholine in and out of season, airway responsiveness to Lolium perenne out of season, and total and specific IgE were assessed. Twelve were male and eight female. Mild asthma was observed in 14, and moderate asthma in six. Age of onset of symptoms ranged from three to 13 years of age. Significant seasonal increase in airway responsiveness to methacholine was found (p = 0.002). Specific bronchial challenge test was positive in all patients. Lolium pernne PD20 ranged from 2.3 to 155.5 inhalation units. An inverse association between age of onset of symptoms and severity of asthma was shown (p = 0.001). Increase in nonspecific bronchial responsiveness was related to the appearance of symptoms during the spring, but it showed no relationship to the severity of symptoms. Severity of asthma during the spring correlated with the intensity of allergen 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 by bronchial response to allergens. Bronchial hyperresponsiveness to methacholine during the spring can be the consequence of environmental exposure to allergens. The intensity of airway responsiveness to methacholine has no predictive value in the severity of pure extrinsic childhood asthma.