Assessment of Eosinophils and Eosinophil Cationic Protein in Induced Sputum in Childhood Asthma

Kim, Woo Kyung; Lee, Hae Ran; Yoon, Hae Sun

Abstract

PURPOSE: Airway inflammation is a characteristic feature of asthma. Sputum analysis can be used as a non-invasive tool to assess severity of the airway inflammation. This study was performed to compare relationships between sputum eosinophils to other parameters of airway inflammation and to evaluate the clinical utility of sputum eosinophils and ECP in childhood asthma.
METHODS
Twenty one ashtmatic children and age matched control subjects without history of allergy were enrolled in this study. Their age was from 21 months to 15 years old. The study was performed from January to April of 2001. Ultrasonically nebulized hypertonic saline was used to induce sputum from children. The children were pre-treated with bronchodilator and peak expiratory flow rate (PEFR) was monitored thought-out the procedure. Sample were analysed for total cell count, differential cell count and for concentrations of eosinophil cationic protein (ECP).
RESULTS
Asthmatic subjects had a significantly higher proportion of blood eosinophils than the control subjects (279.8+/-187.7/mm3 and 26.5+/-18.5/mm3, P<0.01). Correspondingly, percentages of eosinophil and concentration of ECP were 5.10+/-8.79% and 99.85+/-70.10 microL/L in asthmatic and 0.20+/-0.42% and 1.02+/-2.54 microL/L in control subjects (P<0.01 and P<0.01). Serum eosinophils have no correlation with sputum eosinophils or sputum ECP. There was no correlation between sputum eosinophils and ECP either.
CONCLUSION
This study suggests that the proportion of eosinophils and the level of ECP in induced sputum may be sensitive and accurate means of assessing the airway inflammation in childhood asthma, and their relationships with serum eosinophils or serum ECP are to be studied further.