All issues > Volume 35(7); 1992

Original Article

J Korean Pediatr Soc. 1992;35(7):957-970. Published online July 15, 1992.

Late Asthmatic Responses(LARs) and Consequences on Nonspecific Bronchial Reactivity(NSBR) after Exercise and Allergen Challenges in the Children with Bronchial Asthma

Kyung A KA Yoon¹, Young Y. YY Koh¹

¹Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea

Abstract

Exercise and allergen challenges are the main tools to investigate the bronchial responsiveness in experimentally provoked asthma. It is recognized that LAR, which often follows early asthmatic response(EAR) by 3 to 10 hours after challenge, is more closely related to the basic pathogenetic mechanisms operating in bronchial asthma. Although exercise induces an EAR within the first hour similar to allergen provocation, there are some controversy and uncertainty as to LARs after exercise in contrast to those after allergen. In order to 1)evaluate prevalence and define the pattern and characteristics of LARs to exercise and allergen in children with bronchial asthma and 2)analyze their consequences on the NSBR, we subjected asthmatic children, above 7 years of age, who showed methacholine sensitivity, to allergen(Dermatophagoides pteronyssinus extract) or exercise (outdoor maximal free running for 10 minutes) provocation. Of those, subjects who had EAR (25 to exercise and 26 to allergen) were recruited to check pulmonary function hourly for 10 hours and to measure the methacholine sensitivity after-wards. The results were as follows; 1) The prevalence of LAR after exercise(20%) were lower than that(84.6%) after allergen provocation, although, the time and duration of the response after exercise were similar to those after allergen. 2) In the dual responders, the intensity of LAR is lower than that of EAR after exercise, whereas after allergen the intentsities of the two responses are similar. 3) The atopic status affected the prevalence or pattern of LAR after neither exercise nor allergen provocation. 4) Neither EAR nor late maximal response was correlated with the degree of baseline bronchial reactivity in both exercise and allergen provocations. 5) There may be a correlation between EAR and late maximal response after exercise, while it is not the case after allergen povocation. 6) The bronchial reactivity was increased in most cases of dual responder not only after allergen but also exercise provocation. Though low in the occurrence and intensity, LAR after exercise is an important phenomenon on the point that the response is prolonged and associated with increases in NSBR. We can suppose that at least in children, such LAR may reflect the type of inflammatory reaction observed after allergen challenge. If then, this can lead to a subsequent worsening of asthma and increase in medication need to control symptoms.

Keywords :Late Asthmatic Response, Exercise, Allergen, Bronchial Hyperreactivity