An immunohistological evaluation of Pseudomonas aeruginosa pulmonary infection in two patients with cystic fibrosis.

Pseudomonas aeruginosa is the principal pulmonary pathogen in patients with cystic fibrosis. All attempts to date to prevent or eradicate P. aeruginosa infections in these patients have been unsuccessful. Vaccination against P. aeruginosa has been proposed as a preventive strategy but it has not been adequately evaluated. The purpose of this study was to determine whether P. aeruginosa, present in the lungs of patients with cystic fibrosis, express surface antigens similar to those grown in vitro; this issue is of critical importance when choosing bacterial products as vaccine candidates. Lung sections from two patients who died of the pulmonary complications of cystic fibrosis were studied. Bacteria, both in lung sections and isolated from the lung sections and grown in vitro, reacted strongly with polyclonal and monoclonal antibodies against P. aeruginosa mucoid exopolysaccharide and outer membrane proteins F and H2; this suggested that these antigens are surface exposed in vivo. It was also found that bacteria in both lung sections were associated in situ with IgG, IgA, and C3 but not with IgM or C4.