The relationship of serum-eosinophil cationic protein and eosinophil countto disease activity in children with bronchial asthma

Background. The serum-eosinophil cationic protein level (S-ECP) has been pr omoted as a biomarker of asthma that reflects the degree of bronchial eosin ophilic inflammation. Patients and methods. To investigate whether S-ECP is indeed a clinically u seful objective parameter, especially in mild or moderate chronic childhood asthma, we studied 100 outpatient children with chronic asthma symptoms (6 3 boys and 37 girls, aged three to 15 years, median of age eight) and 25 co ntrols (12 boys and 13 girls aged three to 15 years, median of age eight). Symptom scores, lung function parameters and atopy were compared with S-ECP determined by commercially available tests and eosinophils measured by an autoanalyser. Results. Asthma symptom scores in the patient group ranged between one and 13 (median of 8), S-ECP between 2.1 and 75.6 mu g/l (median of 13.3 mu g/l) , and eosinophils between 30/mu l and 2002/mu l (median of 314). Symptom sc ores and S-ECP were correlated significantly (P < 0.001) as were symptom sc ores and eosinophils (P = 0.001). S-ECPs were significantly higher in child ren with chronic asthma symptoms compared with non-asthmatic, non-atopic ch ildren (P = 0.005 for non-atopic chronic asthmatics and P < 0.001 for atopi c asthmatics); similar results were found comparing eosinophils in these gr oups. There was no difference in S-ECP between atopic and non-atopic asthmatic ch ildren, but the 25 polysensitised asthmatic children especially with sensit isations to mite, pollen and pet allergens were found to have significantly higher S-ECP compared to 15 monosensitised children (P = 0.002). Similar r esults were found when correlating eosinophil numbers with atopy. Polysensitised (mite, pollen, pet) asthmatics had significantly higher eosi nophil counts compared with monosensitised (pollen) asthmatics (P = 0.01); there was, however a better discrimination between atopic and nonatopic ast hmatics (P = 0.001). Non-asthmatic, non-atopic controls had significantly l ower eosinophil counts compared with asthmatics (P < 0.001 for both non-ato pic and atopic asthmatics). No correlation between S-ECP or eosinophils and any of the lung function parameters measured (FEV1, FEV1/FVC, MEF50, airwa y resistance and ITGV) was found. Summary. Our data thus indicate that 1) S-ECP is higher than normal in chil dren with asthma symptoms and correlates with asthma symptom score. 2) S-EC P is better correlated to symptom score than to lung function parameters es pecially in children with mild and moderate asthma symptoms. 3) Raised S-EC P appears to reflect the extent of allergen sensitivity and may also reflec t current allergen exposure. 4) Similar correlations were seen when measuri ng eosinophil number by an autoanalyser instead of S-ECP. Conclusions. Although S-ECP and eosinophils are not diagnostic of asthma th ey are useful inflammation markers especially in the context of clinical st udies. However, both methods are not yet suitable for use in daily practice because they require extensive procedures and special equipment.