title: Demonstration of cross-reactive antibodies to smooth gram-negative bacteria in antiserum to Escherichia coli J5.
abstract: We investigated the discrepancy between the broad cross-protection against gram-negative infections afforded by antiserum to Escherichia coli J5 and its apparently narrow cross-reactivity in vitro. Rabbits immunized with J5 bacteria produced antibodies to both the J5 lipopolysaccharide (LPS; titer by ELISA, 1:60,000) and LPS from the Re mutant of Salmonella minnesota (i.e., to the ketodeoxyoctonate [KDO] and lipid A determinants; titer, 1:3,200). In highly diluted antiserum, titers of antibody to J5 LPS were reduced by 28%-41% after adsorption with seven strains of smooth gram-negative bacteria and by only 4% after adsorption with the Re mutant. Smooth gram-negative bacteria adsorbed virtually all antibody to Re LPS. Therefore, rabbit antiserum to J5 contains type-specific antibodies to core determinants distal to KDO that can obscure highly cross-reactive antibodies to lipid A-KDO in vitro. Cross-reactive antibodies are demonstrable by adsorption with whole bacteria at limiting concentrations of antibody.
mesh_terms: D000327:Adsorption; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000276:immunology*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis; D004926:Escherichia coli / Q000276:immunology*; D006090:Gram-Negative Bacteria / Q000276:immunology*; D007106:Immune Sera / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology; D011817:Rabbits
chemical_list: D000907:Antibodies, Bacterial; D000939:Epitopes; D007106:Immune Sera; D008070:Lipopolysaccharides