Properdin: emerging roles of a pattern-recognition molecule.
Complement is an innate immune system that is a first line of defense against pathogens and facilitates elimination of apoptotic and injured cells. During complement activation, the complement convertases are assembled on target surfaces and initiate their proteolytic activities, a process that marks targets for phagocytosis and/or lysis. The complement alternative activation pathway has been implicated in a number of autoimmune conditions including arthritis and age-related macular degeneration. Properdin, a plasma component that is also released by activated neutrophils, is critical in the stabilization of alternative pathway convertases. Recently, it has been shown that properdin is also a pattern-recognition molecule that binds to certain microbial surfaces, apoptotic cells, and necrotic cells. Once bound to a surface, properdin can direct convertase formation and target uptake. New studies are now focusing on a role for properdin in inflammatory and autoimmune diseases. This review examines the new properdin findings and their implications.
Kemper
Claudia
C
MRC Centre for Transplantation, King's College London, United Kingdom. claudia.kemper@kcl.ac.uk
Atkinson
John P
JP
Hourcade
Dennis E
DE
D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology; D003167:Complement Activation; D003165:Complement System Proteins / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D011414:Properdin / Q000737:chemistry / Q000276:immunology*
D011414:Properdin; D003165:Complement System Proteins