Anti‐C1q Antibodies in Juvenile‐Onset Systemic Lupus Erythematosus

Abstract

The objective of this study was to evaluate the presence of anti-C1q antibodies Hospital Israelita Albert Einstein Research Institute, São Paulo, Brazil in 67 juvenile systemic lupus erythematosus (JSLE) patients and 26 healthy controls and to assess the association of these antibodies with disease activity, nephritis, and presence of anti-double-stranded (ds)DNA. Anti-C1q antibodies were detected by ELISA. A higher frequency of anti-C1q antibodies was observed in JSLE patients compared to controls (20% vs. 0%, P = 0.016). Specificity of these antibodies was 100%[95% confidence interval (CI) 86.7-100%] and sensitivity was 19.4% (95% CI 10.7-30.8%) for a lupus diagnosis. The median anti-C1q antibodies was higher in JSLE patients compared to controls [median (range) 9.4 (5.5-127) vs. 7.3 (5-20) units, P = 0.004]. Remarkably, a positive Spearman's coefficient was found between anti-dsDNA and anti-C1q units (r = 0.42, P = 0.0004, 95% CI 0.19-0.60). Our results confirm a low frequency of anti-C1q antibody in our lupus populations, but the presence of anti-Clq antibodies appears to be a good marker for JSLE diagnosis.

The non-classical functions of the classical complement pathway recognition subcomponent C1q

“…Rosen and co-workers suggested that a considerable number of lupus autoantigens were clustered within apoptotic blebs [49,50]. This condition is further compounded by the presence of anti-C1q autoantibodies detected in the sera of a number of patients suffering from SLE [51][52][53][54][55]. The CRT binds to the CD91 and C1q, which is known to bind to the CRT through its collagenous "tail", forms a complex with CRT/CD91.…”

Markers of childhood lupus nephritis indicating disease activity

“…Though, various studies have shown relationships between complement consumption and SLE disease activity, most have been done in adults [22][23][24]. Studies in children with LN are limited and restricted to the analysis of individual parameters [25,26].…”

Pediatric Immunological Disorders Biorepository (PIDBioRep) at University of São Paulo Medical School, Brazil

“…In addition, researchers have used clinical-laboratory information and human biological samples collected by this facility, resulting in a series of works. 3,4,[8][9][10][11][12][13][14][15] Therefore, as a pioneer initiative, this clinical-laboratory database and biorepository will supply researchers with important information and an apparatus that can illuminate the causative factors of autoimmune diseases and primary immunodeficiencies. …”