Beyond lysis: how complement influences cell fate.
Complement is a central component of the innate immune system involved in protection against pathogens. For many years, complement has been known to cause death of targets, either indirectly by attracting and activating phagocytes or directly by formation of a membrane pore, the membrane attack complex. More recently, it has been recognized that complement may cause other 'non-classical' effects that may not directly be aimed at killing of pathogens. Products of complement activation collaborate with the adaptive immune system to enhance responses to antigens. The membrane attack complex of complement, apart from lysing cells, can also trigger diverse events in target cells that include cell activation, proliferation, resistance to subsequent complement attack and either resistance to, or induction of, apoptosis. Various complement products play important roles in signalling for clearance by phagocytes of apoptotic self cells. Here we review some of these non-classical activities of complement and stress the roles that they may play in maintaining the integrity of the organism.
Cole
Duncan S
DS
Department of Medical Biochemistry and Immunology, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK.
Morgan
B Paul
BP
D017209:Apoptosis / Q000276:immunology; D001424:Bacterial Infections / Q000276:immunology*; D001433:Bacteriolysis / Q000502:physiology; D018957:CD59 Antigens / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D002470:Cell Survival; D015936:Complement C5a / Q000502:physiology; D015938:Complement Membrane Attack Complex / Q000276:immunology*; D003165:Complement System Proteins / Q000502:physiology*; D006801:Humans; D010586:Phagocytes / Q000502:physiology*
D018957:CD59 Antigens; D015938:Complement Membrane Attack Complex; D015936:Complement C5a; D003165:Complement System Proteins