Polysaccharide antigens of Pseudomonas aeruginosa.

The major polysaccharide antigens of P. aeruginosa are the cell-wall lipopolysaccharides many of which have an acidic polysaccharide chain (O-antigen) rich in unusual amino sugars. The D-rhamnose-rich polysaccharide antigen common to many serologically distinct strains is also associated with the lipopolysaccharide. The high-molecular-weight polysaccharides with O-specificity are present in extracellular slime produced by strains isolated from the environmental and from the immunocompromised hosts. The extracellular antigenic polysaccharide of another type (bacterial alginate) is expressed by mucoid strains isolated from patients with cystic fibrosis. Serotype-specific immune responses after infection are directed at the lipopolysaccharides and these heat-stable antigens serve as the basis for differentiation of P. aeruginosa strains. Both the cell-wall antigens including conjugates of the O-polysaccharides with different proteins and the extracellular antigens have been used to prepare specific antibodies tested for protection against infections due to P. aeruginosa.