Changes in blood levels of eosinophil cationic protein and tryptase after exercise challenge in adolescents with exercise-induced asthma.

BACKGROUND Exercise-induced asthma (EIA) is increasingly encountered among school children in Kuwait. Available evidence has shown that inflammatory mediators may be involved in the pathogenesis of EIA. Studies on release of inflammatory mediators have been carried out in adult patients with asthma in Kuwait, but no study on EIA involving children has taken place in this region. OBJECTIVE To investigate changes in the concentration of some of the mediators involved in EIA in adolescent school children, using exercise challenge. DESIGN Prospective, case control study. SETTING Respiratory and Cardiology units Mubarak Hospital, Kuwait, between January and June 2001. SUBJECTS Nine EIA and 14 non-EIA and 10 normal control subjects, designated as groups one, two and three aged between 13 and 17 years, who were non-smokers, were enrolled for the study. MAIN OUTCOME MEASURES Blood eosinophils (EOS), eosinophil cationic protein (ECP) and tryptase were estimated pre-exercise, 5 and 30 minutes after exercise. Spirometry was measured at the same period. RESULTS In group one, ECP and tryptase levels fell after exercise, but significant difference in the levels were obtained only in tryptase between pre-exercise and 30 minutes after exercise (4.1 microg/L Vs 3.8 microg/L) P <0.05, while the difference for ECP was not significant (P=0.09). In group two, both tryptase (6.0 microg/L Vs 5.7 microg/L) P < 0.05, and ECP (21.8 microg/L Vs 12.1 microg/L) P<0.01, fell after exercise. However, in group three, no appreciable difference was observed between pre and post exercise. Correlation between tryptase and EOS (r=0.770; P<0.05) and between tryptase and ECP (r=0.850; p<0.05) was observed pre-exercise and after exercise in groups one and two. CONCLUSION A fall in the level of the mediators was observed after exercise challenge, but the relevance of this finding in the pathogenesis of EIA remains unclear. Further studies are required to verify this finding.