Salmonella O antigen-specific oligosaccharide-octyl conjugates activate complement via the alternative pathway at different rates depending on the structure of the O antigen.
Artificial Salmonella serogroup B, D or Cl-specific glycolipids were prepared by covalently linking oligosaccharides corresponding to two O-antigen repeating units, obtained by phage enzyme hydrolysis of native O-antigenic polysaccharides, to octyl residues. Sheep erythrocytes coated with the artificial glycolipids were studied for their ability to consume C3, when incubated in C4- deficient guinea pig serum. Salmonella C1 (0-6,7) glycolipid-coated erythrocytes consumed C3 40% more efficiently than Salmonella D (0-9,12) glycolipid-coated erythrocytes, and 10-times more efficiently than Salmonella B (0-4,12) glycolipid-coated erythrocytes. These results resemble C3 consumption by Salmonella C1, D, and B cells and by sheep erythrocytes coated with purified lipopolysaccharides of these O-specificities. The results prove directly that in a particulate system C3 activation via the alternative pathway depends on the structural properties of the O-antigenic side chain. Structures as small as octasaccharides, or as two O-antigenic repeating units, are sufficient for triggering C3 activation, but the magnitude of activation depends on the nature of the monosaccharides. Apparently, neither the core oligosaccharide nor Lipid A of lipopolysaccharide are required for C3 activation via the alternative pathway.
Laboratory of Structural Biology, National Institute of Arthritis, Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
N
N
Grossman
S B
SB
Svenson
L
L
Leive
A A
AA
Lindberg
D000818:Animals; D000942:Antigens, Bacterial / Q000737:chemistry / Q000276:immunology*; D002240:Carbohydrate Sequence; D003176:Complement C3 / Q000378:metabolism; D003170:Complement Pathway, Alternative / Q000276:immunology*; D004912:Erythrocytes; D006168:Guinea Pigs; D008070:Lipopolysaccharides / Q000276:immunology; D008969:Molecular Sequence Data; D019081:O Antigens; D012475:Salmonella / Q000276:immunology*
D000942:Antigens, Bacterial; D003176:Complement C3; D008070:Lipopolysaccharides; D019081:O Antigens