Evaluation of serum eosinophil cationic protein as a predictive marker for asthma exacerbation in patients with persistent disease

Background Eosinophilic inflammation is a feature of asthma. However, serological markers to indicate eosinophil activation in this process are not fully defined. Objective To evaluate the relationship of serum eosinophil cationic protein (ECP) to asthma worsening and a marker for treatment effectiveness, 26 adult patients with an asthma exacerbation were identified. Methods Identified asthma subjects were treated with oral corticosteroids (prednisone) for 14 days. The lung function variables, forced expiratory volume in one second (FEV1 ) and peak expiratory flow (PEF), were determined as percentage of predicted and the blood total eosinophil count and serum ECP levels were measured. Patients were re-evaluated after 14 days of corticosteroid treatment and then every 3 months thereafter during a 12-month period. Results Eighteen patients responded to prednisone treatment, whereas eight did not, assessed as improvement of their lung function parameters. Different serum ECP patterns could be seen in the responders compared with the non-responders. All 18 responders had considerably increased serum ECP at the time of exacerbation, whereas the non-responders had lower serum ECP levels. The serum ECP levels decreased to a greater extent in the responder patient group than in the non-responder patients following prednisone treatment. This difference in patterns was not seen with total blood eosinophil counts. Conclusion Our findings suggest that serum ECP may be used to predict a response to corticosteroid therapy in adult patients with asthma.