EFFECT OF REGULAR INHALED BECLOMETHASONE ON EXERCISE AND METHACHOLINEAIRWAY RESPONSES IN SCHOOL-CHILDREN WITH RECURRENT WHEEZE

The role of airway inflammation in the pathogenesis of asthma in child hood is uncertain. In the present study, 27 atopic and nonatopic child ren aged 7-9 yrs who had greater than or equal to 5 episodes of wheeze and symptoms of exercise-induced asthma (EIA) in the previous 12 mont hs, performed a methacholine challenge and exercise test on seperate d ays at monthly intervals. The subjects had not received oral or inhale d corticosteroids for 12 months prior to the study, The dose-response relationship to inhaled methacholine was expressed as the cumulative d ose provoking a 20% decrease in forced expiratory volume in one second (PD20), Forced expiratory volume in one second (FEV1) and peak expira tory now (PEF) were measured exercise-induced asthma prior to the exer cise test and at 0, 3, 5, 10, 15 and 20 min following maximal exercise . Following the first methacholine challenge and exercise test, the ch ildren were randomized in a double-blind manner to receive inhaled bec lomethasone dipropionate(BDP) 200 mu g b.i.d. or a placebo b.i.d from a Diskhaler(R) for 3 months. All children were asymptomatic at the tim e of testing, and there was no significant change in the baseline FEV1 of any subject prior to either challenge throughout the study period, When compared to placebo, the bronchial responsiveness to exercise an d methacholine was significantly attenuated in the children who had re ceived inhaled BDP for at least 1 month, There was no relationship bet ween the bronchial responsiveness to methacholine and exercise, There was no significant difference in the bronchial responsiveness to eithe r stimulus in the atopic and nonatopic children. The results of this s tudy suggest that immunoglobulin E (IgE)- and non-IgE-mediated airway inflammation are important in exercise- and methacholine-indnced bronc hoconstriction in children with recurrent wheeze although it is probab le that different mechanisms are responsible.