title: Anti-C1q in systemic lupus erythematosus.
abstract: C1q is the first component of the classical complement pathway. Both clinically validated in-house ELISA assays as well as commercial ELISA kits are used for detection of anti-C1q antibodies. Anti-C1q autoantibodies can be detected in a wide range of autoimmune diseases and are highly sensitive for hypocomplementemic uticarial vasculitis. In SLE, anti-C1q are strongly associated with proliferative lupus nephritis, and their absence carries a negative predictive value for development of lupus nephritis of close to 100%. Anti-C1q in combination with anti-dsDNA and low complement has the strongest serological association with renal involvement. The anti-C1q titers correlate with global disease activity scores in patients with renal involvement, and higher titers seem to precede renal flares. After the successful treatment of a renal flare, anti-C1q has the tendency to decrease or even become undetectable. The main obstacle to the inclusion of anti-C1q in the classification criteria and clinical management of SLE is the lack of standardized laboratory assays.
authors.affiliation: Division of Rheumatology, Beth Israel Deaconess Medical Center, Boston, MA, USA.
authors.forename: G
authors.initials: G
authors.lastname: Stojan
authors.affiliation: Division of Rheumatology, Johns Hopkins University, Baltimore, MD, USA mpetri@jhmi.edu.
authors.forename: M
authors.initials: M
authors.lastname: Petri
mesh_terms: D000974:Antibodies, Antinuclear / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D015922:Complement C1q / Q000276:immunology*; D003171:Complement Pathway, Classical / Q000276:immunology*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications*; D008181:Lupus Nephritis / Q000276:immunology*; D012720:Severity of Illness Index
chemical_list: D000974:Antibodies, Antinuclear; D015415:Biomarkers; D015922:Complement C1q
keywords: C1q; SLE; Systemic lupus erythematosus; anti-C1q; lupus nephritis