Eosinophil cationic protein (ECP) correlates with eosinophil cell counts in the induced sputum of elite swimmers

Abstract

Introduction: Swimming practice has been associated with eosinophilic inflammation, however the underlaying mechanisms are not fully understood. The eosinophil cationic protein in induced sputum may be used as a potential biomarker to assess airway eosinophilic inflammation among elite swimmers. The objective of this study is to characterize eosinophil cationic protein levels in sputum supernatant in elite swimmers and evaluate eosinophil cationic protein as an eosinophilic inflammatory marker. Material and Methods: Elite swimmers annually screened in our department (n=27) were invited to participate in this cross-sectional study. Swimmers who agreed to participate (n=24, 46% girls) performed lung function and skin-prick tests. Induced sputum was also collected and analyzed for differential cell counts and eosinophil cationic protein measurements in sputum supernatant (ImmunoCAPTM 100, ECP, Thermo Fisher Scientific, Uppsala, Sweden). Results: The median eosinophil cationic protein level was 15.60 μg/L (6.02-38.75 μg/L) and higher levels were found among boys (27.90 (11.20-46.30) μg/L vs 6.65 (2.82-22.80) μg/L, p=0.02). In addition, eosinophil cationic protein levels in the sputum supernatant were positively correlated with eosinophil cell counts in the induced sputum (r = 0.583, p = 0.08). Discussion: The measurement of eosinophil cationic protein in sputum supernatant may be a useful marker to assess and manage eosinophilic inflammatory changes in the airways of elite swimmers. Conclusion: Eosinophil cationic protein levels correlated positively with eosinophil counts in the induced sputum in elite swimmers.