Anti-C1q autoantibodies specific against the globular domain of the C1qB-chain from patient with lupus nephritis inhibit C1q binding to IgG and CRP

C-reactive protein, immunoglobulin G and complement co-localize in renal immune deposits of proliferative lupus nephritis

“…Radanova et al recently demonstrated that anti-C1q antibodies from LN patients may inhibit the interaction of C1q with immobilized CRP and IgG [56]. As regards classical complement activation by surface-bound CRP, we have previously shown that this can be prevented by sufficiently high levels of fluid-phase CRP, which consumes C1q [34].…”

C1q, antibodies and anti-C1q autoantibodies

“…The need of using high salt conditions was overcome by using the collagen-like part of C1q rather than the intact C1q molecule (Antes et al, 1988;Wener et al, 1989) or more recently linear peptides from this region (Vanhecke et al, 2012). Using dedicated experiments, anti-C1q antibodies that only target the globular head regions of C1q were more recently also described (Tsacheva et al, 2007) with possibly important functional consequences (Radanova et al, 2012).…”

Functional Characterization of Autoantibodies against Complement Component C3 in Patients with Lupus Nephritis

“…The disease progression is associated with the presence of autoantibodies that recognize various self-molecules, including dsDNA, nuclear proteins, ribosomal proteins, and complement component C1q (1)(2)(3). These autoantibodies may appear as a result of an immune response induced by an inefficient clearance of apoptotic cells and cellular debris, which serve as a source of autoantigens.…”