[Measurement of serum and sputum eosinophil cationic protein concentrations in asthma]

Concentrations of eosinophil cationic protein (ECP) were measured in serum from patients with asthma, patients with chronic obstructive pulmonary disease (COPD), and healthy subjects. The relationships between serum ECP concentration and percent of predicted FEV1 (%FEV1), and between serum and sputum ECP concentrations were also examined in patients with asthma. Serum ECP concentration in asthma was significantly higher than those in COPD patients and healthy subjects. There was a significant inverse correlation between serum ECP concentration and %FEV1 when analysis was restricted to data from asthma patients less than 60 years old. ECP concentration in serum and in sputum were significantly correlated. These results suggest that in asthma patients, eosinophils are activated in serum, and that the degree of eosinophil activation in the airway can be estimated by measuring serum ECP to some extent. Because it does not require bronchial biopsy or bronchoalveolar lavage, measurement of serum ECP may be useful as a minimally invasive monitoring of asthma.