Immunochemistry of Pseudomonas aeruginosa lipopolysaccharides and high-molecular-weight polysaccharides

A comparison was made of the immunochemical properties of high-molecular-weight polysaccharide (PS) and lipopolysaccharides (LPS) from Pseudomonas aeruginosa immunotype 1 and 2 (IT-1 and IT-2) strains. High-molecular-weight PS was found to be an immunogenic, nontoxic form of the LPS serotype determinant found on the O side chain of the LPS. PS and O side chains were serologically identical. Immunization of animals with either whole bacterial cells or purified PS or LPS resulted in comparable levels of antibody directed at PS or O side chains. Chemical analysis of PS and LPS indicated the presence of monosaccharides in PS preparations that are not present in LPS, while PS and LPS share other monosaccharides. PS also lacks core-type sugars found in LPS such as 2-keto-3-deoxyoctulosonic acid, heptose, and glucosamine. PS from IT-1 P. aeruginosa is immunogenic in humans, with essentially no toxicity noted.