Anti-C1q antibodies in systemic lupus erythematosus

• Published in: Lupus Vol. 24; no. 1; pp. 42 - 49
• Main Authors: Orbai, A-M, Truedsson, L, Sturfelt, G, Nived, O, Fang, H, Alarcón, G S, Gordon, C, Merrill, JT, Fortin, P R, Bruce, I N, Isenberg, D A, Wallace, D J, Ramsey-Goldman, R, Bae, S-C, Hanly, J G, Sanchez-Guerrero, J, Clarke, A E, Aranow, C B, Manzi, S, Urowitz, M B, Gladman, D D, Kalunian, K C, Costner, M I, Werth, V P, Zoma, A, Bernatsky, S, Ruiz-Irastorza, G, Khamashta, M A, Jacobsen, S, Buyon, J P, Maddison, P, Dooley, M A, Van Vollenhoven, R F, Ginzler, E, Stoll, T, Peschken, C, Jorizzo, J L, Callen, J P, Lim, S S, Fessler, B J, Inanc, M, Kamen, D L, Rahman, A, Steinsson, K, Franks, A G, Sigler, L, Hameed, S, Pham, N, Brey, R, Weisman, M H, McGwin, G, Magder, L S, Petri, M
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.01.2015; Sage Publications Ltd
• Subjects: Adult; Antibodies; Antibodies, Antinuclear - blood; Basic Medicine; Case-Control Studies; Clinical Medicine; Complement C1q - immunology; Complement System Proteins - deficiency; Cross-Sectional Studies; DNA - immunology; Epidemiology; Female; Hospitals; Humans; Immunologi inom det medicinska området; Immunology; Immunology in the medical area; Klinisk medicin; Lupus; Lupus Erythematosus, Systemic - ethnology; Lupus Erythematosus, Systemic - immunology; Lupus Nephritis - ethnology; Lupus Nephritis - immunology; Male; Medical and Health Sciences; Medical research; Medicin och hälsovetenskap; Medicine; Medicinska och farmaceutiska grundvetenskaper; Microbiology in the medical area; Middle Aged; Mikrobiologi inom det medicinska området; Pathogenesis; Proteinuria - blood; Reumatologi och inflammation; Rheumatic Diseases - immunology; Rheumatology; Rheumatology and Autoimmunity; Sensitivity and Specificity; Young Adult; New York; Istanbul Turkey; United Kingdom > UK; United States > US; Oklahoma; Canada; Los Angeles California; Sweden; Manitoba Canada; Turkey; Quebec Canada; Toronto Ontario Canada; Baltimore Maryland; Anti-dsDNA antibodies; renal lupus; systemic lupus erythematosus
• ISSN: 0961-2033; 1477-0962; 1477-0962
• DOI: 10.1177/0961203314547791

Objective Anti-C1q has been associated with systemic lupus erythematosus (SLE) and lupus nephritis in previous studies. We studied anti-C1q specificity for SLE (vs rheumatic disease controls) and the association with SLE manifestations in an international multicenter study. Methods Information and blood samples were obtained in a cross-sectional study from patients with SLE (n = 308) and other rheumatologic diseases (n = 389) from 25 clinical sites (84% female, 68% Caucasian, 17% African descent, 8% Asian, 7% other). IgG anti-C1q against the collagen-like region was measured by ELISA. Results Prevalence of anti-C1q was 28% (86/308) in patients with SLE and 13% (49/389) in controls (OR = 2.7, 95% CI: 1.8–4, p < 0.001). Anti-C1q was associated with proteinuria (OR = 3.0, 95% CI: 1.7–5.1, p < 0.001), red cell casts (OR = 2.6, 95% CI: 1.2–5.4, p = 0.015), anti-dsDNA (OR = 3.4, 95% CI: 1.9–6.1, p < 0.001) and anti-Smith (OR = 2.8, 95% CI: 1.5–5.0, p = 0.01). Anti-C1q was independently associated with renal involvement after adjustment for demographics, ANA, anti-dsDNA and low complement (OR = 2.3, 95% CI: 1.3–4.2, p < 0.01). Simultaneously positive anti-C1q, anti-dsDNA and low complement was strongly associated with renal involvement (OR = 14.9, 95% CI: 5.8–38.4, p < 0.01). Conclusions Anti-C1q was more common in patients with SLE and those of Asian race/ethnicity. We confirmed a significant association of anti-C1q with renal involvement, independent of demographics and other serologies. Anti-C1q in combination with anti-dsDNA and low complement was the strongest serological association with renal involvement. These data support the usefulness of anti-C1q in SLE, especially in lupus nephritis.