Urinary excretion of leukotriene E-4 and eosinophil protein X in children with atopic asthma

Measurement of leukotriene E-4 (LTE4) in urine is a noninvasive method for assessing changes in the rate of total body cysteinyl leukotriene productio n. Eosinophil protein X (EPX) has been used to assess eosinophil activity a nd monitor inflammation in bronchial asthma. The aim of the study was to lo ok for differences in urinary LTE4 and EPX concentrations between children with stable atopic asthma and healthy controls and to compare asthmatic chi ldren,vith different disease severity. In addition the relationship was eva luated between urinary LTE4 and EPX levels and lung function. LTE4 was also measured (enzyme immunoassay) together with EPX (radioimmunoa ssay) in urine and lung function tests were carried out in children,vith mi ld asthma (steroid-naive) (n=49), moderate to severe asthma (using inhaled steroids) (n=31) and healthy control subjects (n=28), Urinary leukotriene E-4 (LTE4) was significantly higher in children with as thma than in controls (median [25-75 percentile] 238.5 (126.5-375.7) SD 191 .8 versus 189 (51-253.2) SD 131.7 pg . mg(-1) creatinine; p=0.021). Urinary EPX was also significantly increased in asthmatic children compared with c ontrols (85.5 [64-131.5] SD 76.2 versus 48.5 [43.2-90] 112.1 mug.mmol(-1) c reatinine; p=0.006). There were no differences in urinary LTE4 and EPX betw een the group of mild and the group of moderate to severe asthmatic childre n, There were significant associations between the urinary LTE4 and intrath oracic gas volume (ITGV), residual volume (RV), forced expiratory volume in one second (FEV1), forced expiratory capacity (FVC) and maximum expiratory flow rate at 25% of vital capacity (MEF25). Urinary EPX was only correlated with maximum expiratory flow rate at 75% of vital capacity (MEF75). Thus measurement of urinary LTE4 may predict the d egree of airflow obstruction in asthmatic children. Urinary LTE4 and EPX ar e useful markers of airway inflammation and can be helpful in guiding asthm a management. There was no correlation between LTE4 and EPX levels.