Granulocyte proteins in serum in childhood asthma: relation to spirometry and therapy

Abstract

Measurement of markers of eosinophil activation in asthmatics provides information indicative of ongoing inflammatory processes in the airways. This study was conducted to determine the correlations between serum markers of allergic inflammation with spirometry parameters in asthmatic children in different treatment groups. Blood eosinophils, serum levels of eosinophil cationic protein (ECP), eosinophil protein X (EPX), myeloperoxidase (MPO) and tryptase were measured simultaneously with serial measurements of FEV1/FVC, FEF25-75 and FEF in 60 children with acute asthma on admission and after 2, 14, 30 and 60 days. Group A received bronchodilators only (n = 20), group B received sodium cromoglycate (SCG) (n = 20) and group C received oral and/or inhaled corticosteroids (n = 20). Oral steroid treatment (2 mg/kg/day), given at the onset of the asthma attack, resulted in significant reduction in the ECP and EPX levels in all the children. However, these reduced ECP and EPX levels were not sustained in the children, even in those who continued on maintenance steroid treatment. Significant, but inconsistent, correlations between ECP, EPX with total eosinophil count, Percentage eosinophils and spirometry parameters were observed at the different time-points. Tryptase levels were normal in all subjects. There were no significant correlations between myeloperoxidase levels and the spirometry parameters or eosinophil parameters. Serial monitoring of ECP and EPX levels was found to be of some use in predicting clinical outcome in certain steroid-dependent asthmatics (group C) but of no value in the mild asthmatics (group A). While elevation of ECP, EPX and MPO in the serum of childhood asthmatics suggests ongoing inflammation and may inversely correlate with spirometry parameters in some patients, the relationship between these markers and airway function is not a simple one.