Salmonella, complement and mouse macrophages.
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.
Mäkelä
P H
PH
National Public Health Institute, Helsinki, Finland.
Hovi
M
M
Saxén
H
H
Valtonen
M
M
Valtonen
V
V
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*
D000942:Antigens, Bacterial; D019081:O Antigens; D003165:Complement System Proteins