Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Anti-C1q Antibodies Are Associated with Global Activity of Systemic Lupus Erythematosus, but Not Specifically with Nephritis.

Okamoto1,  Yuko, Katsumata5,  Yasuhiro, Kawaguchi2,  Yasushi, Miyake5,  Kohei, Kawamoto5,  Manabu, Takagi5,  Kae, Gono5,  Takahisa

Tokyo Women's Medical University, Tokyo, Japan
Tokyo Women's Medical University, Tokyo, Japan
Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan
Tokyo Women's Medical University, Kamakura Kanagawa, Japan
Tokyo Women's Medical University

Purpose:

Antibodies against complement C1q (anti-C1q Abs) are frequently found in patients with autoimmune diseases such as systemic lupus erythematosus (SLE). It has been reported that they correlate with the occurrence and activity of nephritis and cutaneous vasculitis in SLE. Additionally, their pathogenic role in SLE, such as direct link with apoptosis, has been suggested. However, the significance of anti-C1q Abs in SLE has not been fully characterized. This study was conducted to investigate associations between anti-C1q Abs and clinical and serological parameters of SLE.

Methods:

Anti-C1q Abs were measured using ELISA kit (BÜHLMANN Laboratories AG, Schönenbuch, Switzerland) in sera of 126 consecutive active SLE patients who were admitted to our university hospital from 2007 through 2009. Sera of patients with high-titer anti-C1q Abs at initial evaluation were re-evaluated when their disease ameliorated (n = 20). Sera of patients with other autoimmune diseases and normal healthy controls were also assessed (n = 20 in each control group). Associations between anti-C1q Abs and clinical and serological parameters of SLE were statistically analyzed.

Results:

The titers and the positivity rate of anti-C1q Abs were significantly higher in patients with active SLE than in patients with rheumatoid arthritis, systemic sclerosis, or normal healthy controls (p < 0.0001 in all comparisons).

Anti-C1q Abs were detected in sera of active SLE patients with various manifestations, which yields sensitivity of 63% and specificity of 90%. Inconsistent with previous reports with fewer samples, the titers or the positivity rate of anti-C1q Abs were not associated with active lupus nephritis (n = 23; p= 0.75 and 1.00, respectively). However, the titers of anti-C1q Abs were mildly correlated with the values of SLEDAI, anti-dsDNA Abs, C3, C4 and CH50 (p < 0.0001 in all comparisons). In addition, the titers of anti-C1q Abs significantly decreased in accordance with clinical amelioration by treatment in the cases with high-titer anti-C1q Abs at initial evaluation (median decrement 85%; p= 0.0008).

Conclusions:

These findings indicate that anti-C1q Abs are associated with global activity of SLE, but not specifically with active lupus nephritis. Moreover, anti-C1q Ab might be useful as a surrogate marker of SLE in cases with this antibody.

To cite this abstract, please use the following information:
Okamoto, Yuko, Katsumata, Yasuhiro, Kawaguchi, Yasushi, Miyake, Kohei, Kawamoto, Manabu, Takagi, Kae, et al; Anti-C1q Antibodies Are Associated with Global Activity of Systemic Lupus Erythematosus, but Not Specifically with Nephritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1184
DOI: 10.1002/art.28950

Abstract Supplement

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