title: Chemical structure and biological activity of endotoxins (lipopolysaccharides) and lipid A.
abstract: Lipopolysaccharides (endotoxins) of gram-negative bacteria consist of two components with distinct physico-chemical character: a heteropolysaccharide and a covalently linked lipid, termed lipid A.  Chemically, lipid A is made up of acylated glucosamine disaccharides, which are interlinked by pyrophosphate bridges.  Lipid A represents the toxic center of lipopolysaccharides.  In rabbits, lipid A also induces pyrogen tolerance as well as pyrogen cross-tolerance.  Fever tolerance can be passively transferred with serum from rabbits immunized with lipid A.  The protective power of lipid A antiserum, however, is only expressed in amimals which have been pretreated with lipid A or lipopolysaccharide, indicating that other than humoral factors, perhaps cellular, also participate in endotoxin tolerance.  Lipid A antiserum also prevents the local Shwartzman reaction in rabbits.  The possible potency of lipid A antiserum to prevent other endotoxin effects such as lethal shock is presently investigated.
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D000936:Antigen-Antibody Complex; D055598:Chemical Phenomena; D002621:Chemistry; D003429:Cross Reactions; D004285:Dogs; D004731:Endotoxins / Q000276:immunology; D005334:Fever / Q000276:immunology; D007106:Immune Sera; D007108:Immune Tolerance; D008055:Lipids / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology; D051379:Mice; D011135:Polysaccharides, Bacterial / Q000276:immunology; D011749:Pyrogens / Q000276:immunology; D011817:Rabbits; D012475:Salmonella / Q000276:immunology; D012710:Serum Albumin, Bovine; D012790:Shwartzman Phenomenon
chemical_list: D000936:Antigen-Antibody Complex; D004731:Endotoxins; D007106:Immune Sera; D008055:Lipids; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; D011749:Pyrogens; D012710:Serum Albumin, Bovine