[Measurement of serum eosinophil cationic protein levels in bronchial asthma].

We investigated the possibility of a relationship between the serum levels of eosinophil cationic protein (ECP) and the clinical parameters in asthma. A specific question was whether or not serum ECP changes with a circadian rhythm. Eighty nine children with bronchial asthma and sixteen normal, non-atopic subjects were studied. Serum ECP, eosinophil counts (Eo) and pulmonary functions were measured 4 or 5 times a day. ECP was quantitated by a specific radioimmunoassay. Serum ECP and Eo were significantly higher in the patients with bronchial asthma than in non-atopic subjects. Serum ECP levels were higher during asthma attacks and at 24 hours after attacks than those in stable conditions (free of attacks for more than 7 days). Although no circadian rhythm was observed in ECP changes, the patients with bronchial asthma showed a significantly greater variation of serum ECP levels than the non-atopic subjects. There was no significant correlation between serum ECP levels and 2- or 8-week attack score before the ECP measurement. These results suggest that serum ECP increases in bronchial asthma, especially in its acute exacerbation phase, and may reflect eosinophil activation in vivo.