Prospective longitudinal study of urinary eosinophil protein X in childrenwith asthma and chronic cough

Airway inflammation is the principal abnormality in asthma and many other r espiratory diseases. Eosinophils are the cells primarily involved in this p rocess. The aim of this study was to analyze sequential changes in urinary eosinophil protein X (EPX) a biological marker of eosinophil activation in asthmatic children and chronic coughers, and to confirm the importance of s uch changes in evaluating the inflammatory process once regular treatment w as initiated. Eighty-eight asthmatic children (AC), 33 children with chronic cough (CC), and 34 control children were included in the study. All those with respirat ory disease underwent allergy tests (serum total IgE, serum-specific IgE fo r common allergens, peripheral blood eosinophil (PBE), and skin prick tests ) and a pulmonary function test (PFT), and had chest X-ray and serum eosino phil cationic protein (s-ECP) and urinary EPX assays. All subjects attended the outpatient clinic every 3 months, irrespective of the treatment prescr ibed following inclusion in this investigation. At baseline, urinary EPX concentrations were higher in children with asthma and those with chronic cough than in controls (mean 171.1 and 131.3, respe ctively, vs. 60.2 mug/mmol creatinine, P < 0.001). CC children had lower eo sinophil counts (0.25 vs. 0.39 x 10(9)/L, P <less than> 0.02) than those wi th asthma. There was no significant difference between the AC and CC groups in urinary EPX and s-ECP levels, s-ECP concentrations were significantly h igher (P < 0.01) in atopic vs. nonatopic patients (44 vs. 29.9 ng/mL), but no significant difference was observed for urinary EPX, Concentrations of u rinary EPX were significantly correlated with s-ECP levels (r = 0.24, P < 0 .025) and with PBE (r = 0.38, P < 0.01). No correlation was found between u rinary EPX values and PFT results. In AC receiving inhaled steroids after t he start of the study, there was a significant reduction after 3 months in urinary EPX (-54, P <less than> 0.02). In contrast, there was no significan t change in PBE levels. Urinary EPX concentrations are sensitive, noninvasive technique that could be useful to the clinician in the evaluation of manifestations of airway in flammation, (C) 2001 Wiley-Liss, Inc.