Monoclonal antibodies specific for Escherichia coli J5 lipopolysaccharide: Cross-reaction with other gram-negative bacterial species

Four monoclonal antibodies against Escherichia coli J5 were studied. Each of these monoclonal antibodies reacted with purified lipopolysaccharides from E. coli J5, the deep rough mutant Salmonella minnesota Re595, Agrobacterium tumefaciens, and Pseudomonas aeruginosa PAO1 as well as with the purified lipid A of P. aeruginosa. Enzyme-linked immunosorbent assay using the outer membranes from a variety of gram-negative bacteria demonstrated that these lipid A-specific monoclonal antibodies interacted with between 84 and 97% of the gram-negative bacterial species tested. One of the monoclonal antibodies, 5E4, was shown to interact with 34 of the 35 outer membrane or lipopolysaccharide antigens tested. Immunoenzymatic staining of Western electrophoretic blots of separated P. aeruginosa outer membrane components was used to demonstrate that antibody 5E4 interacted with a similar fast-migrating band, corresponding to rough lipopolysaccharide, from all 17 serotype strains and all 14 clinical isolates of P. aeruginosa. Similarly, iodinated goat anti-mouse immunoglobulin was used to detect the binding of monoclonal antibody 8A1 to a fast-migrating band on Western electrophoretic blots of purified lipopolysaccharides from Klebsiella pneumoniae and both smooth and rough strains of E. coli, Salmonella typhimurium, and S. minnesota. These results suggest considerable conservation of single antigenic sites in the lipid A of gram-negative bacteria.