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.
Grossman
N
N
Laboratory of Structural Biology, National Institute of Arthritis, Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
Svenson
S B
SB
Leive
L
L
Lindberg
A A
AA
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