[Role of plasma histamine and neutrophil chemotactic factor in exercise-induced asthma]

The mechanism of exercise-induced asthma (EIA) is still controversial, although the role of chemical mediator is strongly suspected. In the present study, 50 asthmatic patients were observed after exercise on bicycle ergometer during dry air breathing, and changes of plasma histamine and neutrophil chemotactic factor (NCF) were measured and effect of anti-allergic drugs was examined. 31 patients developed postexertional bronchoconstriction and their % reduction of FEV1 after exercise correlated significantly with the degree of airway hyperresponsiveness to inhaled methacholine determined by Astograph. Plasma histamine levels were examined in 20 EIA positive cases and 13 EIA negative cases, but no significant changes were observed between pre- and post-histamine levels in either group. On the other hand, NCF was elevated significantly after exercise in both EIA positive and negative cases, but postexertional NCF levels were significantly higher in EIA positive than in EIA negative cases. The relationship between % increase of NCF and the % reduction of FEV1 after exercise was significant (r = 0.472, p less than 0.05). DSCG and Azelastine protected the development of EIA in 14 out on 19 cases and 7 out of 12 cases, respectively. Pretreatment with DSCG significantly reduced the increase of NCF after exercise. These results indicates that one of the chemical mediator, NCF, may play an important role in producing postexertional bronchoconstriction in asthmatic patients.