Activation of the classical complement pathway in human serum by a small oligosaccharide
Dieminger, L.; Schultz, D.R.; Arnold, P.I.
Journal of Immunology 123(5): 2201-2211
1979
ISSN/ISBN: 0022-1767 PMID: 489979 Document Number: 146163
Two small oligosaccharides were hydrolyzed from a native polysaccharide by polysaccharidases indigenous to the venom of the tropical ant Pseudomyrmex sp. after incubation for 5 h at 37.degree. C. They were purified by passage through an ultrafiltration membrane (MW cut-off, 500 daltons), cation exchange chromatography at pH 3 to separate the oligosaccharides from peptides and gel filtration chromatography. The highly purified oligosaccharides contained no amino acids and no polar or nonpolar lipids. The larger oligosaccharide had an estimated MW of 840 daltons; the smaller oligosaccharide's estimated MW was 430 daltons. The larger species was a potent activator of C1 and its action was destroyed by treatment with NaIO4. Analysis of both oligosaccharides by gas chromatography revealed 5 sugars: glucose, mannose, galactose, N-acetyl-glucosamine and N-acetyl-galactosamine. Chemical analyses revealed the presence of reducing sugars in the larger species, but neither contained hexuronic acids. The latter were found in the native polysaccharide. The smaller oligosaccharide may be a monomer of the larger species. After electrophoresis on paper at pH 1.9, the 840 dalton oligosaccharide separated into 2 species: the first, which remained at the origin, contained reducing C atoms; the 2nd migrated toward the cathode and contained no reducing sugars. Both species caused the consumption of C2 in human serum. The oligosaccharide(s) with a MW of 840 daltons is the smallest carbohydrate described that causes activation of the classical C pathway.