Exercise-induced late asthmatic reactions with neutrophil chemotactic activity.

Two adults and 13 children with exercise-induced asthma had both immediate and late reductions in forced expiratory volume in one second (FEV1) after treadmill exercise. The late reactions developed 4 to 10 hours after exercise and in each instance were associated with wheezing or chest tightness (or both). Increases in neutrophil chemotactic activity, measured in the 2 adults and in 11 of the children, accompanied the reductions in FEV1 in all these subjects. In contrast, four other adults with only an immediate fall in FEV1 after exercise had only an initial elevation in neutrophil chemotactic activity, with no subsequent increase for the remaining 24-hour period. The agent responsible for the neutrophil chemotactic activity released during exercise-induced late reactions appeared to be identical to that released during immediate reactions. These observations suggest that some patients with exercise-induced asthma have late reactions that, as in the case of antigen-induced bronchoconstriction, are accompanied by the release of neutrophil chemotactic activity.