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Anti-C1q Autoantibodies in Lupus Nephritis

Authors


Address for correspondence: Dr. R. A. Sinico, Clinical Immunology Unit and Renal Unit, Department of Medicine, Azienda Ospedaliera Ospedale San Carlo Borromeo, Via Pio Secondo, 3 – 20153 Milano, Italy. Voice: +39.02.40222489/2343; fax: +39.02.40222222. renatoalberto.sinico@fastwebnet.it

Abstract

Anti-C1q antibodies are found in a variety of diseases, in addition to systemic lupus erythematosus (SLE), and in 3–5% of normal individuals. In particular, anti-C1q antibodies are detected at a high titer in 100% of patients with hypocomplementemic urticarial vasculitis and in 30–48% of SLE patients. Their titer correlates with active renal disease with a sensitivity of 44–100% and a specificity of 70–92%. An increase in anti-C1q antibody titer has been suggested to be able to predict renal flares in lupus nephritis so that monitoring anti-C1q might be valuable for the clinical management of SLE patients as a noninvasive biological marker. Recently our group studied 228 patients affected by lupus nephritis and found that the association of anti-C1q, C3, and C4, in a multivariate analysis, provided the best prediction of renal flares, particularly in patients with focal and diffuse proliferative lupus nephritis and in the absence of antiphospholipid antibodies.

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