Pulmonary host defense: defects that lead to chronic inflammation of the airway.

Current knowledge of pulmonary host defense can help us to understand the unique relationship between CF patients and P. aeruginosa colonization of the lung. Subtle defects in CF host defense, such as those identified in mucociliary clearance and in the CF IgG opsonin, allow P. aeruginosa to persist. Not all the defects are attributable to the host. In several examples, the defects are induced by P. aeruginosa, presumably in an effort to maintain its foothold. The examples of the latter discussed here have included the effect of pseudomonas-derived products on mucociliary action, alpha 1 PI function, and the formation of ineffective IgG opsonins and immune complexes. Overall, P. aeruginosa is the cause of significant morbidity and, eventually, mortality in these patients. As we approach the identification of the genetic defect central to this disease, it is hoped that we will gain more insight into the pathogenesis of the P. aeruginosa lung lesion in CF and develop more effective ways of preventing P. aeruginosa colonization of the CF patients' lungs.