[Measurement of serum eosinophil cationic protein levels in patients with bronchial asthma--analysis according to various clinical backgrounds].

To evaluate the clinical relevance of serum eosinophil cationic protein (ECP) levels, we measured serum ECP levels in 126 asthmatic children, and investigated its relationship with some of the clinical backgrounds. Serum was separated at 1 hour after blood was drawn, and ECP was measured by radioimmunoassay. Serum ECP levels were significantly higher in the patients who had asthma attack within 24 hours than those who did not, and were higher in the patients who had asthma attack almost everyday for the past two weeks than those who had not. In addition, serum ECP levels were correlated with severity of asthma in the previous year, and the patients who had longer history of asthma showed higher levels of ECP. Among the patients who had asthma attacks at the time of blood sampling, serum ECP levels were higher in the patients in whom the attack lasted less than 12 hours than those more than 12 hours. However, no significant correlations were observed between serum ECP levels and the severities of attacks, between serum ECP levels and eosinophil counts. These results suggest that serum ECP level increases during the asthma attack, especially in its chronic active status. Serum ECP may reflect eosinophil activation in vivo and may be a better parameter than eosinophil counts. It is suggested that the measurement of serum ECP level may be useful to evaluate the clinical status of bronchial asthma.