title: Value of a commercial kit for detecting anti-C1q autoantibodies and correlation with immunological and clinical activity of lupus nephritis.
abstract: BACKGROUND
  The association of anti-C1q antibodies (anti-C1q) with the renal activity of lupus nephritis (LN) and the methods for their determination is still a matter of debate.
  
  
  METHODS
  In 116 serum samples of 66 patients with biopsy proven LN, we aimed: 1) to compare the results of the determination of anti-C1q obtained by a commercial kit with a clinically validated in-house ELISA; 2) to evaluate the correlation of anti-C1q with the most important immunological and clinical parameters employed in LN, i.e., antibodies to dsDNA (anti-dsDNA), C3 and C4 complement component, haemoglobin and haematuria.
  
  
  RESULTS
  Good correlation and agreement between the two methods (r=0.81, p<0.0001; contingency coefficient=0.70, p<0.0001, respectively) were demonstrated. No differences were observed between the two assays by ROC curves comparison. Anti-C1q levels were significantly higher in patients with active LN [44 arbitrary units (AUs)] in comparison to those with inactive LN (23 AUs, p=0.047) and significantly correlated with anti-dsDNA (r=0.44, p<0.0001), complement fractions (C3: r=-0.33, p=0.001; C4: r=-0.29, p=0.003), haemoglobin levels (r=-0.34, p=0.0004) and the number of urinary red blood cells (r=0.26, p=0.01).
  
  
  CONCLUSIONS
  Our results suggest the validity of this commercial assay in detecting anti-C1q and confirm the association of anti-C1q with renal involvement of LN and the importance of introducing this parameter in the analytical panel for the evaluation of LN activity.
authors: Federica
authors: F
authors: de Liso
authors: Caterina
authors: C
authors: Matinato
authors: Cristina
authors: C
authors: Novembrino
authors: Antonella
authors: A
authors: Radice
authors: Francesca
authors: F
authors: Raffiotta
authors: Mariangela
authors: M
authors: Ronchi
authors: Maria Daniela
authors: MD
authors: Croci
authors: Renato Alberto
authors: RA
authors: Sinico
authors: Piergiorgio
authors: P
authors: Messa
authors: Erminio
authors: E
authors: Torresani
authors: Gabriella
authors: G
authors: Moroni
mesh_terms: D001323:Autoantibodies / Q000097:blood* / Q000276:immunology*; D015922:Complement C1q / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008181:Lupus Nephritis / Q000097:blood* / Q000276:immunology*; D011933:Reagent Kits, Diagnostic
chemical_list: D001323:Autoantibodies; D011933:Reagent Kits, Diagnostic; D015922:Complement C1q