NOVEL PSEUDOMONAS PRODUCT STIMULATES INTERLEUKIN-8 PRODUCTION IN AIRWAY EPITHELIAL-CELLS IN-VITRO

Because high concentrations of IL-8 are found in the sputum of cystic fibrosis patients, we hypothesized that Pseudomonas aeruginosa (PA) in duces the production of IL-8 in airway epithelial cells and in monocyt es. Therefore, we incubated the supernatant from PA culture with human transformed bronchial epithelial cells (16-HBE) or with monocytes. Th e culture medium of 16-HBE cells that had been incubated with PA super natant for 6 h had chemotactic activity that was inhibited by an antib ody to human IL-8. The PA supernatant induced IL-8 production by prima ry bronchial epithelial cells, by 16-HBE cells, and by monocytes. Afte r incubation with PA supernatant, 16-HBE cells showed a marked increas e in the levels of IL-8 gene expression. The PA product responsible fo r IL-8 production resisted freezing, boiling, and proteolysis. This pr oduct was not lipid extractable and was present in a 1-kD filtrate. We conclude that a small molecular mass product of PA stimulates IL-8 pr oduction by 16-HBE cells and by monocytes, and that the chemotactic ac tivity produced by 16-HBE cells after exposure to PA is due principall y to IL-8.