Studies on the ability of alginate to act as a protective immunogen against infection with Pseudomonas aeruginosa in animals.

Most patients with cystic fibrosis become colonized and infected with mucoid Pseudomonas aeruginosa. The major component of the mucoid material has been identified as the polysaccharide alginic acid. The present work was undertaken to determine whether antibody to alginate is protective in a model of chronic lung infection with P. aeruginosa in rats. Bacterial clearance was associated with a rise in titers of antibody to alginate. In a number of animals a rise in antibody titers was not seen, and in fact a decrease was noted at 30 days compared with 10 days. This observation suggested the possibility of immune complex formation due to antigen excess. Evidence for immune complex deposition in tissues was obtained by immunofluorescence studies. Thus antibody to alginate may offer strain-dependent protection against chronic lung infection with P. aeruginosa in rats; however, immune complex formation should be considered as a possible consequence of immunization with alginate.