Plasma biomarkers and cystic fibrosis lung disease.

PURPOSE The purpose of this study was to determine whether plasma biomarkers reflect changes in lung function and respiratory exacerbations associated with CF lung disease. METHODS Plasma human leukocyte elastase/alpha1 antitrypsin complex (pHLE complex) values were measured in 28 adult CF patients and 47 healthy volunteers and correlated with forced expiratory volume (FEV1) and forced vital capacity (FVC). pHLE complexes were studied during respiratory exacerbations and after antibiotic therapy. Plasma cytokines and sialic acid were also measured. RESULTS pHLE complexes were increased in CF patients (p < 0.01), were inversely correlated with FEV1 (r = 0.71) and FVC (r = 0.67) and returned to normal levels after intravenous antibiotics (p < 0.001). Plasma cytokines did not correlate with lung function. Total sialic acid increased during CF respiratory exacerbations and decreased after antibiotic therapy. CONCLUSION Plasma sialic acid and pHLE complexes reflect clinically meaningful changes in CF lung disease. In contrast, plasma cytokine levels did not correlate with lung function.