Anti-C1q autoantibodies in lupus nephritis

Ann N Y Acad Sci. 2009 Sep;1173:47-51. doi: 10.1111/j.1749-6632.2009.04746.x.


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.

MeSH terms

  • Autoantibodies / blood*
  • Complement C1q / immunology*
  • Complement C3 / immunology
  • Complement C4 / immunology
  • Enzyme-Linked Immunosorbent Assay / methods
  • Humans
  • Lupus Nephritis / diagnosis*
  • Multivariate Analysis
  • Reproducibility of Results
  • Sensitivity and Specificity


  • Autoantibodies
  • Complement C3
  • Complement C4
  • Complement C1q