Lack of relationship between eosinophil cationic protein and eosinophil protein X in nasal lavage and urine and the severity of childhood asthma in a 6-month follow-up study

Background Recent studies suggest that eosinophil cationic protein (ECP) and eosinophil protein X (EPX) may be valuable markers of airway inflammation in various body fluids of asthmatic children. Most of these studies have relied on a single measure of inflammatory markers. Objective We measured ECP and EPX in nasal lavage fluids (NALF) and urine samples in children with asthma over a 6-month period to study the relationship between inflammatory markers and clinical severity. Methods Fourteen children with mild persisting asthma (mean age 11.7 years, SD 2.2) were recruited. All patients were on therapy including inhaled steroids. For a 6-month period asthma severity was monitored by at least monthly physical examination and pulmonary function tests. Daily morning and evening PEF, asthma symptoms and medication were recorded in diaries for the whole study period. Telephone interviews were performed between visits and additional visits were done in case of an increase in asthmatic symptoms or drop of PEF values under 80% of best value. An exacerbation was defined by a fall of FEV₁ > 10% and an increase in asthma symptoms and additional need of β₂-agonist. NALF and urine samples were obtained at each visit and analysed for ECP (NALF only) and EPX. Results Mean observation time was 186.4 days (SD 19.8). Thirteen patients completed the study. During the study period 11 exacerbations were observed in six patients. No significant associations between PEF, PEF variability (amplitude % of mean), daily symptoms, additional β₂-agonist, FEV₁ and MEF₅₀ and nasal ECP, nasal EPX and urinary EPX were found. However, at exacerbations an average increase of nasal ECP (9.3 vs 50.3 μg/L) and EPX (nasal EPX 36.4 vs 141.7 μg/L, urinary EPX 46.4 vs 74.1 μg/mmol creatinine) was observed. Conclusion Serial measurements of ECP and EPX in NALF and urine samples do not provide additional information for the practical management in monitoring childhood asthma.