Twenty-four “healthy” children of asthmatic parents, 14 boys and 10 girls, aged 7 to 18 years, were included in the study. Seven healthy children of healthy parents, 5 boys and 2 girls, aged 9 to 16 years, served as control subjects. Eight of the 24 children of asthmatic parents had siblings with bronchial asthma or atopy and eight children had allergic rhinitis that was defined by clinical history, increased total eosinophilic count, and increased plasma IgE levels. The children of healthy parents had no atopy and no relatives with atopy. None of the children had experienced any acute respiratory infection at least three months prior to the study.

The following pulmonary (unction tests (PFTs) were performed: forced vital capacity (FVC), thoracic gas volume (TGV), forced expiratory volume in 1 s (FEV,), forced expiratory flow rates at 50 percent (FEF50%) and 75 percent (FEF75%) of FVC, and specific airway conductance (SGaw).

Bronchia] provocation tests (BPTs) were performed in all children with normal findings from PFTs during the allergic season of the year (March and April). Eight atopic and five nonatopic children with increased bronchial response to methacholine received six weeks of treatment with cromolyn sodium, two puffs four times a day. Bronchia] provocation tests were repeated in eight atopic and five nonatopic children after treatment with cromolyn sodium and in two non-atopic children after six weeks without treatment. The BPT with methacholine was performed in the same fashion as described in our previous study. The values of SGaw after each test were expressed as percent change from the baseline after saline solution inhalation, and dose response regression lines were con­structed as the best curve of at least four data points for each subject. Bronchial sensitivity was defined as the dose of methacho­line causing a 35 percent decrease in initial SGaw and the slope was defined as bronchial reactivity.
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Statistical comparisons between the results of the provocation tests before and after treatment with cromolyn sodium were established by Students t test for paired values. The level of statistical significance was chosen at p<0.05.