Cystic fibrosis (CF) is a complex multisystem disorder caused by mutations in a membrane glycoprotein called the CF transmembrane regulator (CFTR), which has as its major function serving as a Cl- channel. The relationship between defects in CFTR and development of lung disease remains incompletely understood. Chronic lung disease, characterized by persistent infection with a peculiar type of Pseudomonas aeruginosa, bronchiectasis, and airway obstruction is the major cause of morbidity and mortality in CF patients. The inflammatory response to the chronic infection resembles that induced by lipopolysaccharide (LPS) and is mediated primarily by cytokines such as tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-6, and IL-8, whose synthesis is activated by the transcription factor nuclear factor kappa B (NF-kappa B). Large numbers of neutrophils dominate the inflammatory response and excessive concentrations of their products create a vicious cycle that becomes injurious rather than protective and eventually claims the life of the patient.