Heparin-binding protein in sputum as a marker of pulmonary inflammation, lung function, and bacterial load in children with cystic fibrosis

BACKGROUND: Cystic fibrosis (CF) is associated with bacterial pulmonary infections and neutrophil-dominated inflammation in the airways. The aim of this study was to evaluate the neutrophil-derived protein Heparin-binding protein (HBP) as a potential sputum marker of airway inflammation and bacterial load. METHODS: Nineteen CF patients, aged 6–18 years, were prospectively followed for 6 months with sputum sampling at every visit to the CF clinic. A total of 41 sputum samples were collected. Sputum-HBP was analysed with ELISA, neutrophil elastase activity with a chromogenic assay, and total bacterial load with RT-PCR of the 16 s rDNA gene. Data were compared to lung function parameters and airway symptoms. RESULTS: HBP and elastase correlated to a decrease in FEV(1)%predicted compared to the patients´ individual baseline pulmonary function (∆FEV(1)), but not to bacterial load. Area under the receiver operating characteristic curve values for the detection of > 10% decrease in ∆FEV(1) were 0.80 for HBP, 0.78 for elastase, and 0.54 for bacterial load. CONCLUSIONS: Sputum HBP is a promising marker of airway inflammation and pulmonary function in children with CF.