title: Chemical and biological characterization of the lipopolysaccharide of Bacteroides fragilis subspecies fragilis.
abstract: Bacterial lipopolysaccharides extracted from Bacteroides fragilis subspecies fragilis lacked 2-keto-3-deoxyoctonate and heptose, sugars which make up part of the inner core of most bacterial endotoxins. Over 98% of the lipid portion of this material could be removed easily with chloroform-methanol and alcohol, a finding which indicates a loose association between the polysaccharide and lipid moieties. The lipopolysaccharides caused gelation of limulus lysate at a concentration significantly higher than that for the endotoxin of Salmonella typhi. None of the extracts was lethal in 10-day-old chick embryos at doses of greater than 200 mug per egg, whereas the endotoxin of Neisseria meningitidis was lethal at a dose of 1.2 mug per egg. The local Shwartzman reaction could not be induced by levels of B. fragilis endotoxin of up to 1,000 mug per rabbit, whereas a (control) endotoxin of S. typhi induced this phenomenon at a level of 3 mug per rabbit. Intact oxygen-killed B. fragilis failed to provoke the local Shwartzman reaction at doses of 2,500 mug. These results indicate that B. fragilis has a lipopolysaccharide different from that of most gram-negative bacteria. Although it retains some of the chemical and biologic properties of classical endotoxin, it seems to lack others. This observation may have significant clinical implications.
mesh_terms: D000818:Animals; D001099:Arachnoid; D001439:Bacteroides / Q000145:classification / Q000276:immunology*; D002642:Chick Embryo; D006539:Heptoses / Q000032:analysis; D008070:Lipopolysaccharides / Q000032:analysis / Q000633:toxicity; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification*; D012790:Shwartzman Phenomenon; D014020:Tissue Extracts
chemical_list: D006539:Heptoses; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; D014020:Tissue Extracts