Anti-C1q antibodies in systemic lupus erythematosus. (January 2015)

• Record Type: Journal Article
• 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;
• Is Part Of: Lupus. Volume 24:Number 1(2015)
• Page Start: 42
• Page End: 49
• Publication Date: 2015-01
• Subjects: Anti-dsDNA antibodies -- renal lupus -- systemic lupus erythematosus; Systemic lupus erythematosus -- Periodicals; 616.772005
• DOI: 10.1177/0961203314547791
• Languages: English
• ISSNs: 0961-2033

Abstract

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.