Characterization of Anti-core Glycolipid Monoclonal Antibodies with Chemically Defined Lipopolysaccharides

Five anti-core glycolipid monoclonal antibodies (MAb) (four against Escherichia coli J5 lipopolysaccharide [LPS] and one against the Re core glycolipid of Salmonella typhimurium) were characterized using LPS from several rough and smooth strains and derivatives of E. coli J5 LPS, obtained by N acetylation and hydrolysis. The MAb against E. coli J5 were not only weakly cross-reactive with clinical isolates, whereas the anti-Re MAb was highly cross-reactive. The MAb differed in their reaction pattern with E. coli J5 LPS. MAb 4-7B5 (immunoglobulin M) and MAb 4-6A1 (immunoglobulin G1) cross-reacted with LPS of Salmonella minnesota R5 and S. typhimurium Ra and Rc and little with Re and lipid A. The dominant binding site of these MAb was located in the glucose-heptose-heptose region and was independent of phosphate substitution. The MAb 4-9A1 reacted with the terminal part of the core region (glucose-heptose) and was dependent on phosphate substitution of the LPS. The MAb BA7 (immunoglobulin G3) was E. coli J5 LPS specific and reacted with the glucosaminyl-heptose disaccharide. Antibody 8-2C1 was directed against the common parts of LPS, 3-deoxy-D-manno-octulosonic acid, and lipid A, which are not (or only weakly) recognized by the four anti-J5 LPS MAb. Thus, MAb that are not cross-reactive can be directed against at least three different antigenic determinants present on the core oligosaccharide of E. coli J5 LPS.