Eosinophil cationic protein in peripheral blood of pediatric patients with allergic diseases.

We have studied the levels of eosinophil cationic protein (ECP) and tumour necrosis factor (TNF) in peripheral blood obtained from 68 children with bronchial asthma and 11 children with atopic dermatitis. The ECP mean concentrations of the patients were 23.7 +/- 21.4 micrograms/l and 21.2 +/- 18.7 micrograms/l for bronchial asthma and atopic dermatitis respectively, which were significantly higher than the control value, 5.8 +/- 2.3 micrograms/l (P less than 0.005). TNF was unmeasurable in almost all the samples and no significant difference was observed between normal controls and asthmatic children. A significant correlation was observed between serum levels of ECP and blood eosinophil counts in both diseases (r = 0.873; P less than 0.01 and r = 0.740; P less than 0.01, respectively). However, no obvious correlation was observed between serum levels of ECP and IgE levels. ECP levels were significantly reduced by treatment and normalized in parallel with blood eosinophil counts in the patients with total IgE levels less than 800 U/ml. Irrespective of the total IgE levels, the reduction of serum ECP levels was correlated with a decrease in the number of asthmatic attacks and/or improvement of pulmonary function. These results suggest that the ECP levels in peripheral blood indicate an increased activity of eosinophil and would be a more useful marker than eosinophil counts for making clinical analyses and estimating treatment efficacy in paediatric patients with allergic diseases.