Exercise-induced bronchoconstriction does not cause eosinophilic airway inflammation or airway hyperresponsiveness in subjects with asthma

The cysteinyl leukotrienes (LT) C-4, D-4, and E-4 may partially mediate eos inophilic airway inflammation in patients with asthma, High-intensity exerc ise by patients with asthma can result in exercise-induced bronchoconstrict ion, partly due to leukotriene production, but it is still debated whether this causes airway inflammation. Ten subjects completed a randomized, contr olled study to examine the effects of exercise-induced bronchoconstriction on airway inflammatory cells. Subjects completed exercise challenge and met hacholine challenge in random order separated by 1 wk. Spirometry was measu red for 2 h after challenges, and airway responsiveness was measured the da y before and 24 h after each challenge. Blood and sputum samples were obtai ned before, and 2, 4, 7, and 24 h after each challenge for measurement of i nflammatory cells. Nine of the subjects inhaled allergen at least 3 wk befo re or 1 wk after the study. Sputum samples were collected before, 7 h, and 24 h after challenge. The maximum percentage fall in FEV1 was 21.3 +/- 1.5% after exercise, 29.9 +/- 1.5% after methacholine, and 28.9+/-2.7% after al lergen. Exercise had no effect on airway responsiveness or inflammatory cel ls measured in blood or sputum, unlike allergen inhalation, which resulted in significant airway hyperresponsiveness and increases in sputum eosinophi ls (p < 0.05). This study demonstrates that exercise-induced bronchoconstri ction does not cause eosinophilic airway inflammation in subjects with asth ma who develop airway inflammation with the same degree of allergen-induced bronchoconstriction. We conclude that exercise-induced bronchoconstriction does not cause airway inflammation or airway hyperresponsiveness.