Elevated Serum Eosinophil Cationic Protein Levels in Cystic Fibrosis, Pediatric Asthma, and Bronchiolitis

Abstract

Serum levels of eosinophil cationic protein (ECP) may correlate with activity in certain disease states, suggesting that eosinophils and their toxic granular products are involved in the pathogenesis of the disease. The aim of this study was to measure the serum concentration of ECP in patients with cystic fibrosis (CF), pediatric asthma, and viral bronchiolitis. The absolute number of blood eosinophils and IgE levels were determined simultaneously. Serum ECP levels were the highest in CF patients (median, 3101 μg/L, ± 463, N = 18), followed by those with asthma (median, 1113 μg/L, ± 795, N = 10) and those with viral bronchiolitis (median, 1281 μg/L, ± 274, N = 9). Control patients with no infection or lung disease all had ECP levels between 2 and 58 μg/L (median, 3.7 ± 14.7 μg/L, N = 10). The CF patients studied had a significantly higher level of ECP when compared to pediatric asthma and viral bronchiolitis patients (p = 0.008). There was no correlation between the IgE level or absolute eosinophil count and the ECP level. Among the CF patients studied, the forced expiratory volume in 1 second (FEV1) and ECP level did show a significant inverse correlation, (p < 0.01, probability). The finding of elevated ECP levels in CF patients indicates the presence of eosinophil activation in these patients. The correlation between ECP and airflow obstruction suggests a role for activated eosinophils in disease pathogenesis.