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BMC Nephrol. 2013 Mar 19;14:63. doi: 10.1186/1471-2369-14-63.

Serum levels and renal deposition of C1q complement component and its antibodies reflect disease activity of lupus nephritis.

Author information

1
Renal Division, Department of Medicine, Peking University First Hospital; Institute of Nephrology, Peking University; Key laboratory of Renal Disease, Ministry of Health of China; Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing 100034, Peoples' Republic of China.

Abstract

BACKGROUND:

Lupus nephritis is considered to be a principal cause of morbidity and mortality in SLE. Few studies focus on the association between anti-C1q antibodies in circulation and renal C1q deposition in human lupus nephritis. In this study, we detected the serum levels of C1q, presence of anti-C1q antibodies in circulation, renal C1q deposition and further analyzed their associations with clinical and pathological activity in a large cohort of Chinese lupus nephritis patients.

METHODS:

Sera and renal biopsies from 218 consecutive patients with lupus nephritis with long-term follow up data were studied. Sera were tested for levels of C1q and anti-C1q autoantibodies. Associations of levels of C1q, anti-C1q autoantibodies with renal deposition of C1q, clinical and histopathological data and renal outcome were further investigated.

RESULTS:

The levels of serum C1q were significantly lower in lupus nephritis than that in normal controls [33.81 ± 20.36 v.s. 61.97 ± 10.50 μg/ml (P < 0.001)]. The prevalence of anti-C1q antibodies, ratios of glomerular and vascular deposition of C1q in patients with lupus nephritis were 42.7% (93/218), 71.6% (156/218) and 86.2% (188/218), respectively. The serum C1q levels and anti-C1q antibodies were associated with SLEDAI scores (P < 0.001, P = 0.012, respectively), renal total activity indices scores (P < 0.001, P < 0.001, respectively). Granular positive staining of C1q and IgG by immunofluorescence was co-localized almost completely along the glomerular capillary wall and mesangial areas. Patients with anti-C1q antibodies presented with significantly lower serum C1q levels than those without it (23.82 [0.60, 69.62] μg/ml v.s. 37.36 [0.64, 82.83] μg/ml, P < 0.001). The presence of anti-C1q antibodies was associated with the presence of glomerular C1q deposition (P < 0.001), but not with the presence of renal vascular C1q deposition (P = 0.203).

CONCLUSION:

Anti-C1q autoantibodies were closely associated with serum levels of C1q and glomerular deposition of C1q. Kidney is at least one of the target organs of anti-C1q autoantibodies.

PMID:
23510032
PMCID:
PMC3616847
DOI:
10.1186/1471-2369-14-63
[Indexed for MEDLINE]
Free PMC Article
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