Exercise-induced asthma and the generation of neutrophil chemotactic activity.

Heat-stable neutrophil chemotactic activity (HS NCA) has been demonstrated in serum of subjects with asthma after exercise and after allergen inhalation challenge. Heat-labile neutrophil chemotactic activity (HL NCA) has been investigated only after allergen inhalation challenge. In this study, we have measured HS NCA and HL NCA after exercise of 22 adult patients with asthma, 13 of whom had exercise-induced asthma (EIA). In the 13 patients, the effect of pharmacologic pretreatment on the generation of HS NCA and EIA was evaluated in a double-blind study with inhalation of either disodium cromoglycate, terbutaline, or budesonide 15 minutes before exercise. Additionally, the effect of 4 weeks of treatment with budesonide aerosol was evaluated in an open study. A significant increase (p less than 0.01) in HS NCA was found in the patients with EIA with peak activities 15 minutes after exercise. In patients without EIA, the activity of HS NCA was variable. No HL NCA was detectable after exercise. EIA was inhibited by disodium chromoglycate, terbutaline, and 4 weeks of treatment with budesonide. The generation of HS NCA was more or less inhibited by all three drugs with 4 weeks of treatment with budesonide as the most potent regimen. No late-phase asthmatic reactions to exercise were found. It is concluded that only HS NCA is generated after exercise of subjects with asthma and that this production is controlled by antiasthmatic drugs. However, the generation of HS NCA occurs irrespective of EIA.