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 de Liso, Caterina Matinato, Cristina Novembrino, Antonella Radice, Francesca Raffiotta, Mariangela Ronchi, Maria Daniela Croci, Renato Alberto Sinico, Piergiorgio Messa, Erminio Torresani, Gabriella Moroni
• Journal: Clinical chemistry and laboratory medicine (Clin Chem Lab Med) Vol. 53 Issue 11 Pg. 1771-7 (Oct 2015) ISSN: 1437-4331 [Electronic] Germany
• PMID: 25870967 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Autoantibodies
• Reagent Kits, Diagnostic
• Complement C1q

Topics

• Autoantibodies (blood, immunology)
• Complement C1q (immunology)
• Enzyme-Linked Immunosorbent Assay
• Humans
• Lupus Nephritis (blood, immunology)
• Reagent Kits, Diagnostic