Abstract

Bronchopulmonary disease in patients with cystic fibrosis (CF) is a paradigm of neutrophil-dominated airway inflammation. We hypothesized that proinflammatory cytokines contribute to a localized neutrophil-dominated inflammatory state as present in CF airways. In a cross-sectional study, we analyzed 63 sputum samples from 33 CF patients for concentrations of the cytokines interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-8, tumor necrosis factor-alpha (TNF-alpha), and granulocyte-colony stimulating factor (G-CSF) by means of enzyme-linked immunosorbent assay. Furthermore, the activity of neutrophil elastase (NE) in the sputum samples was determined using a specific chromogenic substrate. Compared to sputum samples from 10 healthy controls, there were significantly increased concentrations of IL-1 beta, IL-8 and TNF-alpha in the CF sputum samples. The concentration of IL-8 correlated significantly with NE activity in the CF sputum samples. In CF patients with airways chronically colonized with Pseudomonas aeruginosa, IL-8 concentrations in sputum were significantly enhanced. In glucocorticoid-treated patients, IL-1 alpha and G-CSF sputum concentrations were significantly lower when compared to levels in the other patients. These results show that there are high concentrations of proinflammatory cytokines in CF airways which may contribute to the localized neutrophil-dominated inflammatory state found clinically.