Correlation between serum anti-C1q antibody levels and renal pathological characteristics and prognostic significance of anti-C1q antibody in lupus nephritis.
OBJECTIVE
To investigate the relationship between serum anti-C1q antibody levels and renal pathological characteristics in lupus nephritis as well as the prognostic significance of serum anti-C1q antibody.


METHODS
Seventy-three patients with biopsy-proven lupus nephritis were enrolled. Anti-C1q antibody was measured in serum samples taken within 7 days before renal biopsy and remeasured at the end of the first and the third month after treatment. All patients were followed at least once a month for 3 months. A cross-sectional study analyzed the relationship between serum anti-C1q antibody levels and renal histopathology and nephritic activity, while a longitudinal study evaluated the prognostic significance of anti-C1q antibody levels in lupus nephritis.


RESULTS
Fifty-eight of 73 patients (79.5%) were reported as having positive baseline serum anti-C1q antibody, with a mean level of 95.3 (+/- 55.2) U/ml. Significant differences were found in serum anti-C1q antibody levels between each World Health Organization (WHO) classification of lupus nephritis. The serum anti-C1q antibody level of WHO class IV was the highest. Serum anti-C1q antibody was positively correlated with the active and chronic indices in renal pathology. Patients with persistent high levels or increased titers of serum anti-C1q antibody tended to develop delayed remission in nephropathy. Serum anti-C1q antibody levels before and after treatment were relevant to renal remission, but serum anti-C1q antibody at the end of the third month after treatment was a stronger predictor for the prognosis after adjustment in the Cox's proportional hazards regression model.


CONCLUSIONS
Serum anti-C1q antibody is a valuable noninvasive biological marker for evaluation of renal involvement and lupus prognosis.
Cai
Xiaoyan
X
Department of Rheumatology and Clinical Immunology, First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
Yang
Xiuyan
X
Lian
Fan
F
Lin
Xiaojun
X
Liang
Ming
M
Li
Jianwen
J
Chen
Xiaohui
X
Liang
Liuqing
L
Qin
Shuguang
S
Fu
Junzhou
J
D000328:Adult; D000704:Analysis of Variance; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D015922:Complement C1q / Q000276:immunology*; D003176:Complement C3 / Q000276:immunology; D003430:Cross-Sectional Studies; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007136:Immunoglobulins / Q000276:immunology; D007668:Kidney / Q000276:immunology / Q000473:pathology*; D008137:Longitudinal Studies; D008181:Lupus Nephritis / Q000097:blood / Q000276:immunology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D012720:Severity of Illness Index
D001323:Autoantibodies; D003176:Complement C3; D007136:Immunoglobulins; D015922:Complement C1q