title: [Investigation of the complement system in clinical practice].
abstract: The complement system plays an important role in defence of the host against infection and in the clearance of immune complexes. Defects in complement proteins are often associated with infections or auto/immune complex diseases. Investigation of complement is useful for diagnosis and following of auto-immune diseases. The aim of this Article is to provide an overview of important applications of complement in medicine, emphasizing the role of complement in pathogenesis and the usefulness of measurements of complement proteins in diagnosis and assessment of the evolution of disease states. Emphasis has been placed on practical applications and understanding basic mechanisms of disease. The best screen for complement deficiencies or significant activation is the CH50, which measures total classical pathway activity and the measurement of C3 and C4. The absence or decrease of multiple components is usually due to consumption of complement. Complete lack of CH50 associated with normal C3 antigen is a strong indication for complement deficiency and should be followed up with further tests to determine which component is missing.
authors.affiliation: Service d'Immunologie Biologique, Hôpital Européen Georges-Pompidou, Assistance Publique-Hôpitaux de Paris, 20-40, rue Leblanc, 75908 Paris Cedex 15. veronique.fremeaux-bacchi@hop.egp.ap-hop-paris.fr
authors.forename: Véronique
authors.initials: V
authors.lastname: Frémeaux-Bacchi
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Dragon-Durey
authors.forename: Jacques
authors.initials: J
authors.lastname: Blouin
authors.forename: Luc
authors.initials: L
authors.lastname: Mouthon
authors.forename: Wolf Herman
authors.initials: WH
authors.lastname: Fridman
mesh_terms: D000799:Angioedema / Q000175:diagnosis / Q000276:immunology*; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000276:immunology; D003167:Complement Activation; D003176:Complement C3 / Q000032:analysis; D003181:Complement C4 / Q000032:analysis; D015941:Complement Hemolytic Activity Assay; D003170:Complement Pathway, Alternative; D003171:Complement Pathway, Classical; D003165:Complement System Proteins / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D003449:Cryoglobulinemia / Q000175:diagnosis / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006463:Hemolytic-Uremic Syndrome / Q000175:diagnosis / Q000276:immunology*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology*; D008589:Meningococcal Infections / Q000175:diagnosis / Q000276:immunology; D009345:Neisseria meningitidis; D011414:Properdin / Q000172:deficiency
chemical_list: D003176:Complement C3; D003181:Complement C4; D011414:Properdin; D003165:Complement System Proteins