[Significance of serum anti-Clq Ab in evaluation of lupus nephritis activity and its curative effects of pharmacotherapy on lupus nephritis].
OBJECTIVE
To investigate the significance of serum anti-C1q Ab of evaluation of lupus nephritis activity and its curative effects of cyclophophamide therapy on lupus nephritis (LN).


METHODS
The level of serum anti-C1q antibody of 75 patients with LN was examined by enzyme-linked immunosorbent assay (ELISA) of the 75 patients the incipient cases had never received corticosteroid and immunosuppressant and the recurrent cases had stopped the immunosuppressant treatment for more than 3 months and were treated, if so, with prednisone with the dosage </= 10 mg/d. Thirty-one patients underwent renal biopsy. The patients underwent treatment of cyclophophamide. The relationships between serum anti-C1q Ab level and lupus nephritis activity, renal pathohistology, as well as laboratory parameters were analyzed, followed by further regular follow-up to investigate its influence to the curative effect.


RESULTS
Fifty-five of the 75 patients (73.3%) were anti-C1q Ab positive with the level of (92 U/ml +/- 41 U/ml). The mean time of conversion of urinary protein into negative was 9 months in the positive C1q positive group and 6 months in the C1q negative group. One year after, 25% of those with positive C1q antibody failed to convert into urinary protein negative, and 90% of those with negative C1q antibody converted into urinary protein negative. One year after, 32% of those whose serum C1q antibody remained positive 1 month after the treatment failed to convert into urinary protein negative, and 91% of those whose serum C1q antibody remained positive 1 month after the treatment converted into urinary protein negative. The serum anti-C1q Ab level was positively correlated with the lupus nephritis clinical active index, proteinuria, and titer of anti-dsDNA, and was negatively correlated with the levels of serum C3 and C4. Renal biopsies showed a positive correlation between the serum anti-C1q Ab level and the activity index of renal pathohistology. Multivariate analysis showed that the serum anti-C1q Ab level after treatment were associated with the curative effect and prognosis of LN.


CONCLUSIONS
Serum anti-C1q Ab is not only a good index of lupus nephritis activity, but also reflects renal involvement and curative effect. That serial measurement of serum anti-C1q Ab may provide better clinical strategies for the therapy.
Cai
Xiao-Yan
XY
Department of Rheumatology, the First Municipal People's Hospital, Guangzhou 510180, China.
Yang
Xiu-Yan
XY
Chen
Xiao-Hui
XH
Liang
Liu-Qin
LQ
Guan
Ming-Mei
MM
Qin
Shu-Guang
SG
Fu
Jun-Zhou
JZ
D000328:Adult; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D015922:Complement C1q / Q000032:analysis / Q000276:immunology*; D003176:Complement C3 / Q000032:analysis / Q000276:immunology; D003181:Complement C4 / Q000032:analysis / Q000276:immunology; D003430:Cross-Sectional Studies; D003520:Cyclophosphamide / Q000627:therapeutic use; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008181:Lupus Nephritis / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology*; D008297:Male; D011379:Prognosis; D012720:Severity of Illness Index
D001323:Autoantibodies; D015415:Biomarkers; D003176:Complement C3; D003181:Complement C4; D007166:Immunosuppressive Agents; D015922:Complement C1q; D003520:Cyclophosphamide