title: The role of complement in the development of systemic lupus erythematosus.
abstract: Complement has both beneficial and deleterious roles in the pathogenesis of systemic lupus erythematosus (SLE). On the one hand, patients with SLE present with decreased complement levels and with complement deposition in inflamed tissues, suggestive of a harmful role of complement in the effector phase of disease. On the other hand, homozygous deficiency of any of the classical pathway proteins is strongly associated with the development of SLE. There are two main hypotheses to explain these observations. The first invokes an important role for complement in the physiological waste-disposal mechanisms of dying cells and immune complexes. The second hypothesis is based around the role of complement in determining the activation thresholds of B and T lymphocytes, with the proposal that complement deficiency causes incomplete maintenance of peripheral tolerance. These two hypotheses are not mutually exclusive. In addition, there is evidence for a contribution from other genetic factors in determining the phenotype of disease in the absence of complement.
authors.affiliation: Rheumatology Section, Division of Medicine, Faculty of Medicine, Imperial College, Hammersmith Campus, London W12 0NN, United Kingdom. a.manderson@imperial.ac.uk
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Manderson
authors.forename: Marina
authors.initials: M
authors.lastname: Botto
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Walport
mesh_terms: D000818:Animals; D003165:Complement System Proteins / Q000172:deficiency / Q000276:immunology*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000235:genetics / Q000276:immunology*; D018448:Models, Immunological; D015398:Signal Transduction / Q000276:immunology*
chemical_list: D003165:Complement System Proteins