Airway inflammation and occurrence of delayed bronchoconstriction in exercise-induced asthma

We studied nine asthmatic patients with a history of exercise-induced asthma (EIA) in order to investigate whether inflammatory changes in the airways occur after exercise and are eventually associated with the development of a late-phase asthmatic response. On two separate study days, bronchoalveolar lavage (BAL), bronchial lavage (BL), and bronchial biopsy (BB) were performed 3 h after an exercise or a methacholine (MCh) challenge. On two other separate occasions, FEV₁ was monitored for 12 h after identical exercise and MCh challenges not followed by BAL, BL, and BB. We found a greater percentage of eosinophils in BAL after exercise versus MCh challenge (p <0.05). In five patients, BAL eosinophils after exercise were ≥ 2% of total inflammatory and immunoeffector cells. In three of these patients an FEV₁ fall > 20% of control was recorded 5 to 12 h after exercise. However, two of these patients had 2% or more eosinophils. In BAL and similar late falls of FEV₁ after MCh challenge. The percentage of degranulating mast cells in BB was higher (p <0.05) after EIA than after MCh, but no significant differences were found in BL histamine and leukotrienes. We conclude that (1) exercise may enhance mast cell degranulation and eosinophilic inflammation of the airways, and (2) a delayed bronchoconstriction after exercise is not specific to EIA but is more likely the result of fluctuations in lung function associated with airway inflammation.