A comparison of late reactions to antigen and exercise.

Immediate and late asthmatic reactions may occur after inhalation of specific antigens such as house dust mites or pollens. Recently, similar dual reactions have been found to occur after asthma induced by exercise. The immediate reaction to an antigen is believed to be due to the release of preformed and newly formed mediators derived primarily from mast cells via IgE antibodies. The late reaction also appears to be the result of an IgE reaction but involves inflammation in which cells play a role. The late reaction to antigen is often more severe than the immediate reaction and may be followed by a prolonged period of "nonspecific" bronchial hyperreactivity. By contrast, the late reaction to exercise is usually less severe than the immediate reaction. Both immediate and late exercise reactions are also associated with peaks of neutrophil chemotactic factor activity. Cromolyn sodium administered before challenge modifies both the immediate and the late response to antigen and exercise. Glucocorticoids block the late but not the early reaction to antigens. Their effect on the late exercise reaction is not yet known. Albuterol prevents the initial reaction to both exercise and antigen and may modify the late reaction to exercise as well.