Detection of antibodies to Pseudomonas aeruginosa alginate extracellular polysaccharide in animals and cystic fibrosis patients by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay was developed to detect antibodies to sodium alginate exopolysaccharide purified from three strains of Pseudomonas aeruginosa and commercial alginate from seaweed. Good attachment of alginate occurred with polystyrene microtiter plates at pH 7.0 with 0.04 M sodium phosphate buffer. With the enzyme-linked immunosorbent assay procedure, antibodies to alginate (not previously shown to be immunogenic) could be shown in humans and after immunization of mice and rabbits. Antibody to one of the alginates cross-reacted with two other P. aeruginosa alginates and commercial seaweed alginate. In animal immunization antibody titers were maximal after a single intravenous injection with an optimal dose of P. aeruginosa 3064 alginate. Healthy controls not known to have a previous P. aeruginosa infection had low, but detectable, antibody titers to 3064 and commercial alginate. Three cystic fibrosis patients not colonized with P. aeruginosa had similar antibody levels. Twenty-eight cystic fibrosis patients colonized with P. aeruginosa formed a clearly separate group with antibody titers higher than that of the control and noncolonized cystic fibrosis patients. Antibody titers to 3064 or commercial alginate did not increase during acute P. aeruginosa bronchopneumonitis in 16 cystic fibrosis patients or after repeated episodes in 4 patients.