OBJECTIVE:
We aimed to evaluate the association between eosinophilic inflammation in induced sputum and pulmonary function and persistent airflow limitation in children.
METHODS:
A total of 92 asthmatic children and 72 controls were enrolled in this study. Eosinophil count (%) and eosinophil cationic protein (ECP) levels were measured in induced sputum. We performed spirometry and a methacholine challenge test, and measured total eosinophil count, total serum IgE, and serum ECP in all subjects.
RESULTS:
Asthmatic children had significantly higher levels of sputum eosinophils (9% vs. 0%; P < 0.001) and sputum ECP (2.3 ± 0.7 vs. 1.6 ± 0.6 log µg/L, p < .001) than controls. Sputum ECP levels showed a significant negative correlation with post-bronchodilator (post-BD) FEV(1) (r = -0.307; p = .001) and post-BD FEV(1)/FVC (r = -0.286; p = .002), whereas sputum eosinophils showed no correlation with post-BD FEV(1) and post-BD FEV(1)/FVC. However, no significant differences in sputum ECP and sputum eosinophil counts were observed in asthmatic children with and without persistent airflow limitation.
CONCLUSIONS:
Our findings suggest that sputum eosinophilic inflammation, especially ECP, is associated with pulmonary function and persistent airflow limitation, which is manifested by low post-BD FEV(1)/FVC.