Mediators of hypersensitivity in exercise-induced asthma.

Neutrophil chemotactic factor (NCF) is a slightly acidic macromolecule which is released into the circulation of asthmatic individuals following an exercise task. Its appearance was basophil-independent, accompanied the development of airflow obstruction and its release could be inhibited by administration of disodium cromoglycate. There was no elaboration of NCF after isocapnic hyperventilation with cold air, although the same asthmatics produced NCF following treadmill exercise. Finally, NCF was also released during exercise-induced late asthmatic reactions, as in antigen-induced late responses.