Anti-C1q autoantibodies from active lupus nephritis patients could inhibit the clearance of apoptotic cells and complement classical pathway activation mediated by C1q in vitro.

Abstract

Anti-C1q antibodies are prevalent in patients with active lupus nephritis and were found to be closely associated with renal involvement and predictive for a flare of nephritis. However, the pathogenesis of anti-C1q antibodies involved in human lupus nephritis remains unclear. C1q, which plays a key role in apoptotic cell and immune complex removal, is a very important functional molecule in the pathogenesis of SLE. The aim of this study was to investigate the influence of anti-C1q autoantibodies from active lupus nephritis patients on the bio-functions of C1q in vitro. We purified IgG autoantibodies against C1q from lupus nephritis patients, and found that they could recognize C1q bound on early apoptotic cells at 30 μg/ml, and could significantly decrease the phagocytosis by macrophages of early apoptotic cells opsonized by 50 μg/ml C1q in comparison with normal IgG. Levels of circulating immune complexes of the ten patients were measured by a circulating immune complexes (CIC)-C1q Enzyme Immunoassay Kit. Anti-C1q autoantibodies affinity purified by microtiter plates could significantly inhibit the deposition of C3c on CIC-C1q in a dose dependent manner in comparison with IgG from 10 healthy blood donors. The binding of opsonized immune complexes to RBCs was significantly inhibited by anti-C1q autoantibodies purified by microtiter plates in a dose dependent manner. Our observations suggest that serum anti-C1q autoantibodies from active lupus nephritis patients could interfere with some biological function of C1q in vitro.

• Authors: Yun Pang, Xiao-Wei Yang, Yan Song, Feng Yu, Ming-Hui Zhao
• Journal: Immunobiology (Immunobiology) Vol. 219 Issue 12 Pg. 980-9 (Dec 2014) ISSN: 1878-3279 [Electronic] Netherlands
• PMID: 25092568 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 Elsevier GmbH. All rights reserved.

Chemical References

• Antigen-Antibody Complex
• Autoantibodies
• Complement C1q

Topics

• Adult
• Antigen-Antibody Complex (immunology, metabolism)
• Apoptosis (immunology, radiation effects)
• Autoantibodies (blood, immunology, isolation & purification)
• Cell Line
• Complement C1q (immunology)
• Complement Pathway, Classical
• Cytophagocytosis (immunology)
• Erythrocytes (immunology, metabolism)
• Female
• Humans
• In Vitro Techniques
• Lupus Nephritis (immunology, metabolism, therapy)
• Male
• Middle Aged
• Plasma Exchange
• Ultraviolet Rays
• Young Adult