Eosinophil cationic protein in patients with bronchial asthma

: To evaluate the role of eosinophils in the pathogenesis of bronchial asthma, we measured eosinophil cationic protein (ECP), one of the eosinophil granule proteins. Serum ECP levels were measured by radioimmunoassay in asthmatic (n = 59) and non-asthmatic (n = 47) patients. Preliminary study showed that ECP levels were time-dependently increased in the blood samples until 3 hr. Based on the findings, we determined to measure serum ECP levels at 30 min after blood sampling. Serum ECP levels and blood eosinophil counts in asthmatic patients were significantly higher than those in non-asthmatic patients (p less than 0.01). There was also a positive correlation between serum ECP levels and blood eosinophil counts in patients with asthma (r = 0.46, p less than 0.001). No significant difference was observed in either serum ECP levels or blood eosinophil counts in asthmatic patients classified by clinical type and severity. Blood eosinophil counts in patients with asthma attacks were significantly greater than in those in remission (p less than 0.05), but no significant difference was observed in serum ECP levels between these groups, suggesting an enhanced elimination of ECP during attack. Serum alpha-2 macroglobulins, which bind to ECP and may function as scavengers for ECP, were not significantly different in these group. These results suggest that serum ECP levels may not be a direct indicator of eosinophil activation or degranulation in the pathogenesis of asthma.