Cystic fibrosis, lung infections, and a human tracheal antimicrobial peptide (hTAP).

In order to understand how lungs of healthy people, unlike those of cystic fibrosis (CF) patients, are protected against bacterial infections such as Pseudomonas aeruginosa, the following three key findings were made. First, P. aeruginosa do not multiply when planted onto tracheal epithelial cells from healthy humans but do so profusely on cells from deltaF508 CF patients. Second, some bacteria bind, and gain entrance into CF cells, even at a physiological salt concentration (104 mM). Third, human tracheal epithelial cells express an approximately 4 kDa peptide (hTAP), which is known in its bovine form to exhibit bactericidal action against P. aeruginosa. A model is proposed depicting both how normal epithelial cells, in a first-line self defense mechanism, may be protected against bacterial infection and how this mechanism may fail during the initial stages of CF.