Eosinophil-derived neurotoxin in childhood asthma: correlation with disease severity

Abstract

Background: Eosinophil numbers and eosinophil cationic protein (ECP) levels have been proposed as markers of disease activity; however, the usefulness of eosinophil-derived neurotoxin (EDN)--another eosinophil granular protein--as a marker in pediatric asthma has not been established.

Objective: The authors compared the concentrations of blood eosinophil counts (TECs), serum ECP, and serum EDN to asthma symptom severity in young children.

Methods: Forty-three young children with asthma (Asthma group: mean age, 2.9 years; range, 1.4-5.0 years) were evaluated during both the acute and stable phases of disease. Asthma severity was measured using a symptom-scoring technique, and serum eosinophil indices (EDN and ECP levels and TECs) were determined. Nineteen age-matched controls (Control group: mean age, 2.7 years; range, 1.0-5.0 years) were used for comparison.

Results: Levels of serum EDN, serum ECP, and TECs were significantly higher in children with acute asthma compared with Controls (p < .0001). However, in stable asthma only EDN and ECP levels differed significantly when compared to Controls (p < .0001 and p < .001, respectively). When comparing acute and stable phases, EDN and TECs differed significantly (p < .0001), whereas ECP did not. Symptom scores correlated significantly with EDN (r = 0.850, p < 0.0001), ECP (r = 0.374, p < 0.01) and TECs (r = 0.457, p < 0.01) in acute asthma patients. When symptom scores were divided into three subgroups based on severity, only EDN levels showed significant differences amongst the three groups.

Conclusion: These findings suggest that serum EDN is a useful marker for identifying disease activity in children with asthma. EDN levels may better reflect disease severity than ECP levels or total eosinophil counts.