Protection against mucoid Pseudomonas aeruginosa in rodent models of endobronchial infections.

Chronic endobronchial infection with mucoid Pseudomonas aeruginosa accounts for much of the morbidity and mortality in patients with cystic fibrosis (CF). Reduced morbidity is observed when infection is absent. Clinical investigations have implicated opsonizing antibody specific for the mucoid exopolysaccharide (MEP) surrounding these bacteria as a potential immunologic protective mechanism, whereas nonopsonizing antibody to MEP is not protective. Mice and rats immunized with doses of MEP that elicited opsonizing antibody had reduced levels of infection compared with nonimmune controls after intratracheal challenge with mucoid P. aeruginosa enmeshed in agar beads. Doses of MEP that elicited nonopsonizing antibody were not protective. Parallel experiments in which passive transfer of polyclonal and monoclonal opsonizing and nonopsonizing antibody were used yielded similar results. These data indicate that MEP-specific opsonizing antibody can protect against chronic P. aeruginosa infection in this model of disease.