The potential implication of eosinophil activation in the pathogenesis of childhood asthma

Abstract

Background: Asthma is now recognized as an eosinophil mediated inflammation of the airways. Pulmonary function tests are less easily performed in young children. So, measuring markers of eosinophil activation is of special importance in pediatric practice. Objective: This study aimed at evaluating the role of eosinophil protein X (EPX) as a marker for assessment of asthma attack severity and control of the exacerbation. Methods: Serum EPX was measured in 35 asthmatic Egyptian children aged between 7 and 10 and 35 age and sex matched healthy children using radioimmunoassay technique (RIA). Asthmatic patients were graded according to severity of the attack into mild, moderate and severe and the measurement was performed during and after the resolution of acute asthma attack. In addition, complete hemogram, total serum IgE, arterial blood gases and stool analysis were performed and peak expiratory flow rate (PEFR) was assessed in asthmatic children during and after acute exacerbation. Results: Serum concentrations of EPX, total serum IgE and absolute eosinophilic count (AEC) were significantly higher in asthmatic children than healthy controls (P < 0.001). Serum EPX and AEC were significantly higher in all studied groups before treatment compared to the corresponding levels of the same patients after treatment (P < 0.001). Total serum IgE was significantly higher only in mild and moderate asthma before treatment (P < 0.001). Serum EPX level was significantly elevated among patients with severe attacks (84.70 ± 7.18 μg/L) than those with moderate attacks (67.2 ± 5.31 μg/L) and patients with mild attacks (53.47 ± 11.47 μg/L)(P < 0.001). It was negatively correlated to PEFR measurement during attacks (r=-0.75, P < 0.05). A significant reduction in serum EPX and AEC was observed after the resolution and improvement of pulmonary function. Meanwhile, total serum IgE decreased after treatment with the resolution of asthma attack, yet it remained significantly higher than that of controls (P < 0.001). Conclusion: Our findings support the concept that EPX may be implicated in the pathogenesis of asthma and highlights its importance in monitoring the severity and control of asthma exacerbation. Hence, it might represent an objective guide of treatment efficacy.

Keywords: EPX, Childhood asthma, pathogenesis, eosinophil activation

Egypt J Pediatr Allergy Immunol 2004; 2(1): 52-57