title: Salmonella, complement and mouse macrophages.
abstract: The structure of the polysaccharide chains that constitute the O antigen on the surface of Salmonella bacteria determines the rate of complement activation and C3b deposition on the bacteria. A fast-activating O antigen causes rapid C3-dependent opsonization of the bacteria injected intraperitoneally; as a consequence, the bacteria are taken up and killed by the resident peritoneal macrophages, and their virulence is low. A slow-activating O antigen protects the bacteria from opsonization in the peritoneal cavity, and is associated with higher virulence. However, if injected intravenously bacteria with either O-antigenic type are equally virulent; in the high complement concentration of the blood they become opsonized and taken up by macrophages in the liver and spleen, which are unable to kill them but instead provide a protected site for multiplication.
authors: National Public Health Institute, Helsinki, Finland.
authors: P H
authors: PH
authors: Mäkelä
authors: M
authors: M
authors: Hovi
authors: H
authors: H
authors: Saxén
authors: M
authors: M
authors: Valtonen
authors: V
authors: V
authors: Valtonen
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D003167:Complement Activation; D003165:Complement System Proteins / Q000276:immunology*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D019081:O Antigens; D012481:Salmonella Infections, Animal / Q000276:immunology; D012486:Salmonella typhimurium / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D019081:O Antigens; D003165:Complement System Proteins