Anti-nucleosome antibodies in patients with systemic lupus erythematosus of recent onset. Potential utility as a diagnostic tool and disease activity marker

OBJECTIVE: To compare the utility of anti-chromatin antibodies for the diagnosis of systemic lupus erythematosus (SLE) and as markers of disease activity. METHODS: We included 73 consecutive patients (62 female) with SLE (four or more ACR criteria) of recent onset (<1 yr since diagnosis). As control groups we included 130 healthy blood donors and 261 patients with 11 systemic autoimmune diseases (SAD). Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). A venous blood sample was drawn to measure three anti-chromatin antibodies [anti-nucleosome (anti-NCS), anti-double-stranded DNA (anti-dsDNA) and anti-histones (anti-HST)] by enzyme-linked immunosorbent assay. RESULTS: The prevalence of anti-chromatin antibodies in SLE patients and healthy controls was 100 and 3% respectively for anti-NCS, 63 and 5% for anti-dsDNA, and 15 and 3% for anti-HST. Anti-NCS had a sensitivity of 100% and specificity of 97% for SLE diagnosis. When SLE and SAD patients were compared [excluding mixed connective tissue disease (MCTD)], the sensitivity of anti-NCS, anti-dsDNA and anti-HST antibodies for SLE diagnosis was 93, 71 and 40% respectively and the specificity was 97, 98 and 98%. Anti-chromatin antibodies were not useful in differentiating between SLE and MCTD patients. Anti-NCS antibodies showed the highest correlation with disease activity (r = 0.45, P < 0.0001), especially in patients negative for anti-dsDNA antibodies (r = 0.58, P = 0.001). Anti-NCS antibodies also showed strong association with renal damage (odds ratio 4.1, 95% confidence interval 1.2-13.6, P = 0.01). CONCLUSION: Anti-NCS antibodies could be a useful tool in the diagnosis and assessment of disease activity in SLE patients, especially in patients who are negative for anti-dsDNA antibodies.     

Anti-chromatin and anti-histone antibodies in Egyptian patients with systemic lupus erythematosus

There has been a renewed interest in anti-chromatin and anti-histone antibodies in the last few years. To assess the prevalence of anti-chromatin and anti-histone antibodies in patients with systematic lupus erythematosus (SLE) and to correlate serum levels of these antibodies with clinical features of the disease, the presence of anti-chromatin and anti-histone antibodies in 38 patients with SLE was investigated by an enzyme-linked immunosorbent assay (ELISA). To determine the specificity of these antibodies, 15 patients with rheumatoid arthritis, 15 patients with systemic sclerosis, and 15 normal controls were also tested. Sensitivity of anti-chromatin antibodies in SLE patients was 89.5% and specificity was 80.0%, while sensitivity of anti-histone antibodies was 92.1% and specificity was 82.2%. Significant associations were found between the levels of anti-chromatin antibodies and arthritis, malar rash, oral ulcer, pulmonary affection (P < 0.05) also, lupus nephritis (P < 0.01), and disease activity score as measured by SLE disease activity index (SLEDAI; P < 0.001). Significant association was found between anti-histone antibodies and fatigue (P < 0.05). The incidence of positive anti-chromatin and anti-histone antibodies was significantly higher than that of anti-dsDNA antibodies in early stage of the disease. We conclude that anti-chromatin and anti-histone antibodies are both sensitive and specific for SLE and could be a useful addition to the laboratory tests that can help in the diagnosis of SLE. Anti-chromatin antibodies seem to be a promising marker useful in early diagnosis and assessment of disease activity in SLE patients especially in patients who are negative for anti-dsDNA antibodies. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

三种自身抗体联合检测对狼疮疾病活动和狼疮肾炎的价值

目的探讨联合检测抗C1q抗体、抗核小体抗体(AnuA)和抗dsDNA抗体对狼疮活动和狼疮肾炎(LN)的价值。方法 90例系统性红斑狼疮(SLE)分为疾病活动和疾病稳定组、LN和非LN组, 酶联免疫吸附试验(ELISA)检测血清抗C1q抗体和AnuA水平,间接免疫荧光法比较三抗体单个和联合对疾病活动和LN的价值。结果抗C1q抗体、AnuA和抗dsDNA抗体阳性对疾病活动的敏感性分别为 71．4％、75．0％和66．1％,特异性分别为75．5％、70．6％和88．2％;抗dsDNA抗体阴性患者分别有36．7％抗 C1q抗体阳性和26．5％AnuA阳性。疾病活动组三抗体阳性率和抗体水平显著高于疾病稳定组;三抗体与 SLE疾病活动指数(SLEDAI)、血沉(ESR)、IgG、球蛋白水平显著正相关,与C3、C4及白蛋白水平显著负相关。LN组三抗体水平显著高于非LN组。结论三抗体都是狼疮疾病活动的指标,都与LN有关,联合检测可以提高疾病活动检出率。     

Anti-chromatin antibodies in systemic lupus erythematosus: a useful marker for lupus nephropathy

Background: Anti-chromatin antibodies have recently been described in patients with systemic lupus erythematosus (SLE) and it has been suggested that their presence is associated with lupus nephritis. Objective: To assess the prevalence and clinical associations of these antibodies in SLE. Methods: The presence of anti-chromatin antibodies in 100 patients with SLE was investigated by an enzyme linked immunosorbent assay (ELISA). To determine the specificity of these antibodies, 100 patients with primary Sjögren''s syndrome, 30 with primary antiphospholipid syndrome (APS), 10 with systemic sclerosis, and 100 normal controls were also tested. Results: Positive levels were detected in 69/100 (69%) patients with SLE. In contrast, they were found in only 8/100 (8%) of those with primary Sjögren''s syndrome, in 1/10 (10%) with systemic sclerosis, in 2/30 (7%) with primary APS, and in none of the 100 healthy controls. Patients with anti-chromatin antibodies had a twofold higher prevalence of lupus nephropathy than those without these antibodies (58% v 29%, p<0.01). A significant correlation was found between the levels of anti-chromatin antibodies and disease activity score as measured by the European Consensus Lupus Activity Measurement (ECLAM; p=0.011). Conclusions: The measurement of anti-chromatin antibodies appears to be a useful addition to the laboratory tests that can help in the diagnosis and treatment of SLE. These antibodies are both sensitive and specific for SLE, and are a useful marker for an increased risk of lupus nephritis.     

Anti-C1q antibodies and antiendothelial cell antibodies in systemic lupus erythematosus – relationship with disease activity and renal involvement

The aim of this study was to investigate the relationship between the presence and titre of antibodies against C1q (anti-C1q Ab) and disease activity and renal involvement in patients with systemic lupus erythematosus (SLE). Anti-C1q Ab were measured in 79 patients with SLE (70 women and 9 men; mean age 41.7 years; mean disease duration 8.4 years): 19 patients had active disease with lupus nephritis, 8 active disease without nephritis, 26 inactive disease with nephritis and 26 inactive disease without nephritis. Anti-dsDNA antibodies (EIA and immunofluorescence), antiendothelial cell antibodies (AECA) and complement levels (C3, C4, total haemolytic complement activity) were determined in parallel. Anti-C1q Ab were positive in 49%, anti-dsDNA Ab in 61% and AECA in 19% of the patients, respectively. Significantly higher titres of anti-C1q Ab were found in patients with active disease compared with those with inactive SLE (P < 0.01). Serum levels of anti-C1q Ab showed a positive correlation with anti-dsDNA Ab and SLEDAI score (P < 0.01) and a negative correlation with C3 (P < 0.05), C4 (P < 0.01) and CH50U (P < 0.01). The presence of anti-C1q Ab was not different between patients with or without nephritis. In patients with (P < 0.05) and without nephritis (P < 0.01) the frequency of anti-C1q Ab was significantly higher in active patients compared with inactive patients. Both anti-C1q and anti-ds-DNA Ab were detectable in 74% of patients with active nephritis but only in 30% of all other patients (P=0.001). None of the patients with active nephritis was negative for anti-C1q and anti-dsDNA Ab, whereas 37% of the patients without active nephritis were negative for both antibodies (P < 0.01). Sensitivity, specificity, positive and negative predictive values for active lupus nephritis among SLE patients were 100%, 50%, 51.9% and 100% for anti-dsDNA Ab (EIA) and 74%, 70%, 57% and 89.4% for positive findings of both anti-dsDNA and anti-C1q Ab. The presence and titre of anti-C1q-Ab in SLE are related to disease activity. Absence of anti-dsDNA Ab excludes active nephritis; positive findings of both anti-dsDNA Ab and anti-C1q Ab are of relatively high specificity for active nephritis.     

A prospective study of anti-chromatin and anti-C1q autoantibodies in patients with proliferative lupus nephritis treated with cyclophosphamide pulses or azathioprine/methylprednisolone

OBJECTIVE: To study the prevalence and course of anti-chromatin (anti-nucleosome, anti-double-stranded (ds) DNA and anti-histone) and anti-C1q autoantibodies in patients with proliferative lupus nephritis (LN), treated in a randomised controlled trial with either cyclophosphamide or azathioprine plus methylprednisolone. METHODS: Autoantibody levels were measured and analysed in 52 patients with proliferative LN, during their first year of treatment. Levels in both treatment arms were compared and associations with clinical, serological and outcome parameters were studied. RESULTS: At study entry, prevalences for anti-nucleosome, anti-dsDNA, anti-histone and anti-C1q autoantibodies were 81%, 96%, 23% and 65%, respectively. Anti-chromatin autoantibodies correlated with each other, but not with anti-C1q levels. If patients were divided for their autoantibody titre at the start of treatment above or below the median, the only significant differences were higher SLE disease activity index with higher anti-nucleosome, and higher creatinine with higher anti-C1q autoantibodies. During the first year, a comparable rapid decline in the levels of anti-nucleosome, anti-dsDNA and anti-C1q autoantibodies was seen in both treatment arms. Anti-histone autoantibody levels were low and did not change. Renal flares were not preceded by rises in autoantibody titres. CONCLUSIONS: These results indicate that measurement of anti-chromatin and anti-C1q autoantibodies is useful for diagnosing LN, but not for monitoring disease course.     

Anti-C1q antibodies in nephritis: correlation between titres and renal disease activity and positive predictive value in systemic lupus erythematosus

OBJECTIVE: To investigate antibodies to complement 1q (anti-C1q) and investigate the correlation between anti-C1q titres and renal disease in systemic lupus erythematosus (SLE). METHODS: 151 SLE patients were studied. In patients with biopsy proven lupus nephritis (n = 77), activity of renal disease was categorised according to the BILAG renal score. Sera were tested for anti-C1q by enzyme immunoassay. Serum samples were randomly selected from 83 SLE patients who had no history of renal disease, and the positive and negative predictive value of the antibodies was studied. RESULTS: Patients with active lupus nephritis (BILAG A or B) had a higher prevalence of anti-C1q than those with no renal disease (74% v 32%; relative risk (RR) = 2.3 (95% confidence interval, 1.6 to 3.3)) (p<0.0001). There was no significant difference in anti-C1q prevalence between SLE without nephritis and SLE with non-active nephritis (BILAG C or D) (32% v 53%, p = 0.06) or between active and non-active nephritis (74% v 53%, p = 0.06). Patients with nephritis had higher anti-C1q levels than those without nephritis (36.0 U/ml (range 4.9 to 401.0) v 7.3 U/ml (4.9 to 401.0)) (p<0.001). Anti-C1q were found in 33 of 83 patients (39%) without history of renal disease. Nine of the 33 patients with anti-C1q developed lupus nephritis. The median renal disease-free interval was nine months. One patient with positive anti-C1q was diagnosed as having hypocomplementaemic urticarial vasculitis syndrome during follow up. CONCLUSIONS: Anti-C1q in SLE are associated with renal involvement. Monitoring anti-C1q and their titres in SLE patients could be important for predicting renal flares.     

血清C1q抗体水平与系统性红斑狼疮活动性和狼疮肾炎的关系

目的分析探讨血清C1q抗体水平与系统性红斑狼疮（SLE）活动性以及狼疮肾炎之间的关系。方法采用ELISA方法检测92例SLE患者C1q抗体水平。并与其他SLE活动性指标进行相关分析。结果SLE患者C1q抗体阳性率为67.4%。活动性狼疮组的C1q抗体阳性率及C1q抗体水平显著高于非活动性狼疮组（P〈0.001）。活动性狼疮肾炎组C1q抗体阳性率（P〈0.05）和C1q抗体水平（P〈0.01）显著高于非活动性狼疮肾炎组。联合抗dsDNA抗体检测,没有1例活动性狼疮肾炎患者的C1q抗体和抗dsDNA抗体同时阴性。结论血清C1q抗体与狼疮活动以及活动性狼疮肾炎关系密切,C1q抗体的检测有助于活动性狼疮的诊断,联合抗dsDNA抗体的检测是活动性狼疮肾炎的特异性检测指标。     

Significance of anticardiolipin and anti-beta(2)-glycoprotein I antibodies in lupus nephritis

OBJECTIVE: To investigate whether anticardiolipin (aCL) and anti-beta(2)-glycoprotein I (anti-beta(2)GPI) antibodies are associated with lupus nephritis (group II patients), and whether there are differences in the prevalence of these two autoantibodies between group II patients and patients with non-nephritis SLE (group I) and primary antiphospholipid syndrome (PAPS) patients (group III). METHODS: IgG and IgM aCL were measured in 31 patients and anti-beta(2)GPI in 30 patients with systemic lupus erythematosus (SLE) nephritis and 25 without SLE nephritis and in 36 PAPS patients by validated enzyme immunoassays. Relationships of anti-double-stranded DNA (anti-dsDNA) antibodies and antibodies to the collagenous region of C1q (anti-C1q) with SLE nephritis were also examined. RESULTS: The prevalence and levels were higher for aCL, but not for anti-beta(2)GPI, antibodies in group II than in group I patients. Absolute values of aCL and anti-beta(2)GPI in all three patient groups correlated with each other. The prevalences of aCL, anti-dsDNA and anti-C1q antibodies were significantly higher in group II than in group I and group III patients. CONCLUSION: The observations in this paper suggest that raised levels of aCL antibodies are associated with lupus nephritis. We were not able to demonstrate an association between anti-beta(2)GPI antibodies and kidney disease either in patients with lupus or in patients with primary antiphospholipid syndrome. In SLE, we demonstrated that the presence of anticardiolipin antibodies in conjunction with elevated levels of anti-dsDNA and anti-C1q antibodies is highly specific for glomerulonephritis in patients with lupus.     

Autoantibodies to lipoprotein lipase and dyslipidemia in systemic lupus erythematosus

OBJECTIVE: To demonstrate the binding of bovine lipoprotein lipase (LPL) by IgG from sera obtained from patients with systemic lupus erythematosus (SLE) and other rheumatic diseases, and the relationship of anti-LPL to triglyceride levels in SLE. METHOD: Binding of LPL by IgG from sera obtained from patients with SLE and other rheumatic diseases was measured by an enzyme-linked immunosorbent assay technique. Lipid profiles for fasting blood samples obtained from SLE patients and control subjects were determined. RESULTS: Sera obtained from 105 patients with SLE were assessed for reactivity with LPL, and 49 (47%) of the results were positive. Sera obtained from patients with rheumatoid arthritis (RA) (n = 80), Sj?gren's syndrome (n = 30), polymyositis and dermatomyositis (n = 30), and progressive systemic sclerosis (n = 31) were also studied, and 10 (13%), 3 (10%), 12 (40%), and 13 (42%), respectively, were positive for reactivity with LPL. It was determined that all affinity-purified anti-double-stranded DNA (dsDNA) antibodies and 4 of 5 monoclonal anti-dsDNA antibodies bound to LPL. The binding of IgG depleted of anti-dsDNA to LPL indicates a second anti-LPL activity in SLE. Measurements of fasting lipid levels in SLE patients with anti-LPL revealed a strong positive correlation of antibody levels and total serum triglycerides, apolipoprotein B, and apolipoprotein E concentrations. CONCLUSION: Antibodies to LPL occurred in 47% of SLE patients and in a similar percentage of patients with polymyositis or systemic sclerosis. The prevalence of these antibodies was less in patients with RA or Sj?gren's syndrome. It is hypothesized that the elevated triglyceride levels in SLE patients are in part attributable to anti-LPL, and this lipid abnormality could contribute to the premature atherosclerosis known to be present in patients with SLE.     

Nonrenal and renal activity of systemic lupus erythematosus: a comparison of two anti-C1q and five anti-dsDNA assays and complement C3 and C4

Associations of different assays for antibodies to C1q (anti-C1q) and to dsDNA (anti-dsDNA) and of complements C3 and C4 with disease activity in patients with systemic lupus erythematosus (SLE) were studied. The clinical manifestations of 223 SLE patients were recorded, and the disease activity was assessed by the SLEDAI score. Anti-C1q were determined by two enzyme-linked immunosorbent assays (ELISA) and anti-dsDNA by a radioimmunoassay (RIA), a Crithidia immunofluorescence (IF) assay and three ELISA assays using human telomere DNA, plasmid DNA circles, or calf thymus DNA as antigens, respectively. Complement C3 and C4 were determined by nephelometry. Control sera were obtained from 98 blood donors. In patients with SLE, the prevalence of anti-C1q was 17–18% and that of anti-dsDNA was 36–69%. Anti-C1q, anti-dsDNA, and complement C3 and C4 correlated well with the overall activity of SLE (r?=?0.323–0.351, 0.353–0.566, and ?0.372–0.444, respectively; P?<?0.001). Sensitivity, specificity, positive predictive value, and negative predictive value for active lupus nephritis among SLE patients were 40–44, 92, 29, and 91–92% for anti-C1q and 48–68, 29–66, 11–16, and 86–91% for anti-dsDNA, respectively. Patients with active nephritis had higher levels of anti-C1q and lower levels of C3 and C4 than patients with inactive nephritis (P?=?0.003–0.018). The corresponding associations of anti-dsDNA were somewhat weaker (P?=?0.023–0.198). Hematological parameters reflecting disease activity correlated clearly better with anti-dsDNA and complement C3 and C4 than with anti-C1q. Anti-C1q is inferior to anti-dsDNA as a diagnostic test in SLE and in the evaluation of overall clinical activity of the disease. Anti-C1q together with complement C3 and C4 may offer useful additional information to monitor lupus nephritis activity. There are no practical differences between different assays for anti-C1q and anti-dsDNA.     

Prevalence and clinico-serological correlations of anti-alpha-enolase, anti-C1q, and anti-dsDNA antibodies in patients with systemic lupus erythematosus

OBJECTIVE: To evaluate the prevalence and clinico-serological correlations of anti-enolase, anti-C1q, and anti-dsDNA antibodies in patients with systemic lupus erythematosus (SLE). METHODS: Sixty-eight sera randomly obtained from SLE patients were examined. Anti-alpha-enolase antibodies were detected by immunoblot on recombinant protein; anti-C1q and anti-dsDNA antibodies were detected using an ELISA. RESULTS: Anti-alpha-enolase, anti-C1q, and anti-dsDNA antibodies were positive in 21%, 62%, and 63% of patients, respectively. A correlation was found between anti-dsDNA and anti-C1q antibodies, while anti-enolase antibodies did not correlate with the other 2 specificities. Anti-alpha-enolase antibodies were not correlated with any of the clinical and serological variables examined. Anti-C1q antibodies were correlated with ECLAM score, leukopenia, complement levels, and active renal involvement. Anti-dsDNA antibodies correlated with arthritis, leukopenia, complement levels, and the presence of renal involvement, independent of activity. In patients with active renal disease anti-dsDNA antibodies were correlated with a poor renal outcome, occurring after a mean period of 24 months. CONCLUSION: These data suggest the association of anti-C1q antibodies with disease flares and active renal disease in SLE. The observed association of anti-dsDNA antibodies and renal disease was expected. Further analysis is required to fully assess the clinical significance of anti-a-enolase antibodies.     

Simultaneous detection of anti-C1q and anti-double stranded DNA autoantibodies in lupus nephritis: predictive value for renal flares

Clinical difficulties in predicting systemic lupus erythematosus (SLE) renal flares are still encountered. Biological markers such as autoantibodies (aAbs) may be of major interest for clinicians in the follow-up of SLE patients. The aim of our study was to investigate the clinical utility of one of these biological markers, anti-C1q aAbs, in predicting renal flares of SLE nephritis in comparison with the 'gold standard' anti-double stranded DNA (anti-dsDNA) aAbs. Anti-C1q aAbs and anti-dsDNA aAbs were analysed through a longitudinal retrospective study of 23 SLE patients presenting with one or more renal flares. Anti-C1q and/or anti-dsDNA aAbs were found in 20 (87%) of 23 patients, of whom 16 (69%) displayed both. Thirty-three renal flares occurred during the course of the study, and anti-C1q aAbs and anti-dsDNA aAbs were positive in 25 (76%) and 24 (73%) of these flares respectively. The sensitivity of anti-C1q and/or anti-dsDNA aAbs in predicting renal flares reached 85%. The specificity of anti-C1q aAbs was 84%, of anti-dsDNA aAbs 77% and of both aAbs 97%. Positive and negative predictive values were as follows: 56% and 70% for anti-C1q aAbs, 53% and 72% for anti-dsDNA aAbs. The combination of both aAbs had the highest positive predictive value (69%), whereas absence of both aAbs was associated with the highest negative predictive value (74%). In conclusion, our results confirm that anti-C1q aAbs are present in a significant percentage of SLE patients with active renal involvement, suggesting that these aAbs could be a useful additional marker. The presence of anti-C1q and anti-dsDNA aAbs was associated with a high risk of renal flare, whereas the absence of both aAbs excluded such an event. These data confirm that systematic detection of anti-C1q and anti-dsDNA aAbs is of interest for the follow-up in SLE patients with renal involvement.     

Anti-C1q antibodies in pregnant patients with systemic lupus erythematosus

OBJECTIVE: To study anti-C1q antibodies in pregnant patients with systemic lupus erythematosus (SLE) and to evaluate their prognostic significance for the occurrence of disease flares or pregnancy complications. METHODS: Twenty-one pregnancies in 19 SLE patients prospectively followed were analyzed. Disease activity was evaluated on the basis of the physician's intention to treat and a modified version of the ECLAM index. Anti-C1q and anti-dsDNA antibodies were detected in the sera by an ELISA assay. Antinuclear antibodies, anti-ENA antibodies, anticardiolipin antibodies and lupus anticoagulant were also performed. RESULTS: In all the patients the disease was inactive at the beginning of the pregnancy. Four flares of disease activity were observed in 4 pregnancies (19%) and obstetric complications were encountered in 7 pregnancies (43%). Anti-C1q antibodies were positive in 4 (19%) pregnancies and anti-dsDNA antibodies in 8 (38%). The presence of anti-phospholipid antibodies at the first assessment was correlated with the occurrence of obstetric complications (p<0.05). The presence of anti-C1q and anti-dsDNA antibodies at the first assessment had no prognostic significance for the occurrence of flares or obstetric complications during the course of pregnancy. Although the small number of patients studied did not allow for statistically significant analysis, flares appeared to be more likely to occur in patients presenting with anti-dsDNA or anti-C1q antibodies during pregnancy compared to patients with no changes in these antibody titers (43% vs 8% respectively). CONCLUSIONS: The presence of anti-C1q and anti-dsDNA antibodies does not seem to be prognostic for the occurrence of flares during pregnancy. Further studies are warranted to explore this possibility.     

Association between ongoing anti-C1q antibody production in peripheral blood and proliferative nephritis in patients with active systemic lupus erythematosus

The aim of this study was to compare ongoing production of anti-C1q antibodies (anti-C1q) in peripheral blood with serum anti-C1q levels in patients with systemic lupus erythematosus (SLE), especially in patients with nephritis. Using the ELISPOT technique for the detection of IgG and IgA anti-C1q production, 21 patients with active SLE were investigated. ELISAs for IgG and IgA anti-C1q were compared with the ELISPOT results. Six of the patients were found to have proliferative nephritis (WHO grade III/IV) confirmed by renal biopsy. High numbers of IgG anti-C1q spot-forming cells (SFC), defined as > 20/10(5) plated peripheral blood mononuclear cells (PBMC), were exclusively observed in patients with proliferative nephritis (P < 0.0001). Serum levels of IgG anti-C1q were significantly increased in patients with proliferative nephritis (P = 0.039). High ongoing IgG anti-C1q production was observed in all patients with proliferative nephritis, which may be a contributory factor in the pathogenesis of this disorder. The detection of IgG anti-C1q production may be valuable in the clinical investigation of patients with suspected SLE nephritis.      

An analysis of clinical disease activity and nephritis-associated serum autoantibody profiles in patients with systemic lupus erythematosus: a cross-sectional study.

OBJECTIVE: To establish the correlation between lupus nephritis-associated autoantibody levels and the presence/activity of lupus nephritis and global disease activity using cross-sectional data in patients with systemic lupus erythematosus (SLE). METHODS: Disease activity was assessed using the British Isles Lupus Assessment Group (BILAG) index. Antibody levels against single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), histones, nucleosomes and heparan sulphate (HS) were analysed by ELISA in SLE patients with (n=11) and without (n=22) nephritis and in normal controls (n=21). Antibody subclasses were also analysed. RESULTS: Higher levels of anti-dsDNA and anti-HS antibodies were found in patients with lupus nephritis, the level of anti-HS antibodies correlating with the BILAG renal score. Predominant subclasses were IgG1 and IgG3 for dsDNA antibodies, IgG2 for anti-nucleosome antibodies, and IgG2 and IgG3 for anti-HS antibodies. CONCLUSION: Correlation was demonstrated between antibodies to dsDNA, ssDNA, histones, nucleosomes and HS. There is a strong correlation between the level of anti-HS antibodies and disease activity in patients with lupus nephritis as measured by BILAG.     

Anti-C1q antibodies are associated with systemic lupus erythematosus disease activity and lupus nephritis in northeast of China

This study aimed to investigate the associations of anti-C1q antibodies with systemic lupus erythematosus (SLE) disease activity and lupus nephritis (LN) in northeast of China. Ninety patients with SLE, 37 patients with other autoimmune diseases, and 40 healthy donors in northeast of China were enrolled. Serum anti-C1q antibodies were measured by ELISA with 20 RU/ml as the threshold of positive results. The prevalence and levels of anti-C1q antibodies in SLE group (50%, 20.54 ± 34.67 RU/ml) were significantly higher than those in autoimmune disease and healthy control groups (P < 0.05), yet no significant difference between LN patients and non-LN lupus patients (57.14% vs 41.46%, P > 0.05; 25.92 ± 39.94 vs 13.07 ± 27.39 RU/ml, P > 0.05). Anti-C1q antibody levels were positively correlated with levels of Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, anti-dsDNA, and anti-cardiolipin and negatively correlated with serum C3 and C4 (P < 0.05). The prevalence of anti-Sm and anti-nucleosome increased in anti-C1q-positive lupus patients (P < 0.05). Compared with anti-C1q-negative lupus patients, patients with 20–40 RU/ml anti-C1q antibodies had comparable disease activity (P > 0.05); patients with 40–80 RU/ml anti-C1q antibodies had significantly lower levels of serum complement (P < 0.05); patients with above 80 RU/ml anti-C1q antibodies had much more severe hypocomplementemia, increased SLEDAI scores, and higher incidence of hematuria and proteinuria (P < 0.05). Furthermore, the specificity and positive predictive value of 80 RU/ml anti-C1q antibodies for LN was 97.56% and 87.50%, respectively. In conclusion, anti-C1q antibodies are associated with SLE and LN disease activity, and the contribution hinges on the titers. Moreover, high-level anti-C1q antibodies are valuable for diagnosing LN.     

抗C1q抗体与系统性红斑狼疮疾病活动及狼疮肾炎的关系

目的研究抗C1q抗体与系统性红斑狼疮（systemic lupus erythematosus,SLE）疾病活动及肾损害的相关性。方法使用ELISA法测定93例初诊SLE患者和69例其他风湿性疾病患者及32名健康对照者血清中抗C1q抗体的浓度。同时记录SLE疾病活动指数（systemic lupus erythematosus Disease Activity Index,SLEDAI）、自身抗体和相关实验室指标。结果血清抗C1q抗体、抗dsDNA抗体、抗核小体抗体（anti-nucleosome antibodies,AnuA）,SLE组的阳性率分别为40.9%、62.4%和62.8%。血清抗C1q抗体阳性组患者的肾损害发生率（84.2%）明显高于阴性组（23.6%）。狼疮肾炎（lupus nephritis,LN）患者血清抗C1q抗体浓度（55.36±51.96）RU/ml及阳性率（71.1%）显著高于无肾炎表现的狼疮对照组（12.09±14.46）RU/ml,12.5%。无论患者有无肾损害,狼疮疾病活动患者抗C1q抗体浓度（62.46±50.29）RU/ml及阳性率（85.7%）显著高于疾病稳定的狼疮对照组（8.79±6.42）RU/ml,3.9%。而AnuA和抗dsDNA抗体只在伴有狼疮肾损害的疾病活动组即活动LN的阳性率（87.9%与50.0%）显著高于非活动LN对照组（66.7%与33.3%）。LN组抗C1q抗体、AnuA、抗dsDNA和抗Sm（Smith）抗体阳性率显著高于非LN组（71.1%与12.5%）,（77.8%与47.9%）,（57.8%与25.0%）,（31.1%与10.4%）。SLE疾病活动组抗C1q抗体、AnuA、抗dsDNA阳性率显著高于疾病稳定组（85.7%与3.9%）,（88.1%与41.2%）,（61.9%与17.6%）。活动LN抗C1q抗体、AnuA、抗dsDNA阳性率显著高于非活动LN（93.9%与8.3%）,（87.9%与50.0%）,（66.7%与33.3%）。活动LN组抗C1q抗体、AnuA、抗dsDNA及抗中性粒细胞胞质抗体（ANCA）阳性率显著高于其他SLE组（93.9%与13.1%）,（87.9%与48.3%）,（66.7%与26.7%）,（43.5%与8.5%）。结论血清抗C1q抗体能够反映SLE的疾病活动,并与SLE肾损害相关,是对活动性LN敏感的自身抗体。     

血清抗C1q抗体与狼疮肾炎活动性及病理改变的相关性

目的 探讨血清抗C1q抗体与狼疮肾炎(LN)肾组织病理改变的相关性,以及对LN的活动性的评价.方法 用酶联免疫吸附法(ELISA)检测活动期LN患者60例和非LN患者60例血清中的抗C1q抗体,分析这一抗体与LN肾组织病理改变、活动指数及其他实验室参数的相关性.结果 LN患者血清抗C1q抗体水平(89±26)U/ml较非LN患者(57±23)U/ml高(P＜0.01);60例LN患者有同期肾活检病理资料,按世界卫生组织(WHO)分型,Ⅱ型12例,Ⅲ型14例,Ⅳ型18例,Ⅴ型16例.经方差分析显示,各病理类型问抗C1q抗体水平差异有统计学意义,其中以Ⅳ型LN的抗C1q抗体水平显著高于其他病理类型(P＜0.01);C1q在肾组织的沉积与血清抗C1q抗体水平相关;血清抗C1q抗体水平与肾脏病变的活动指数(AI)及尿蛋白含量呈正相关(P＜0.01),与补体C3、C4水平呈负相关(P＜0.01);抗双链DNA(dsDNA)抗体阳性的SLE患者,血清抗C1q抗体水平高于抗dsDNA抗体阴性者(P＜0.01).结论 血清抗C1q抗体水平在一定程度上反映LN肾脏的病理改变,并与肾脏病变活动指数有相关性,检测血清抗C1q抗体对评价LN病情及指导治疗有临床实用价值.     

Antihistone and anti-double-stranded deoxyribonucleic acid antibodies are associated with renal disease in systemic lupus erythematosus

PURPOSE: We sought to assess the nephritogenic antibody profile of patients with systemic lupus erythematosus (SLE), and to determine which antibodies were most useful in identifying patients at risk of nephritis. METHODS: We studied 199 patients with SLE, 78 of whom had lupus nephritis. We assayed serum samples for antibodies against chromatin components (double-stranded deoxyribonucleic acid [dsDNA], nucleosome, and histone), C1q, basement membrane components (laminin, fibronectin, and type IV collagen), ribonucleoprotein, and phospholipids. Correlations of these antibodies with disease activity (SLE Disease Activity Index) and nephropathy were assessed. Patients with no initial evidence of nephropathy were followed prospectively for 6 years. RESULTS: Antibodies against dsDNA, nucleosomes, histone, C1q, and basement membrane components were associated with disease activity (P <0.05). In a multivariate analysis, anti-dsDNA antibodies (odds ratio [OR] = 6; 95% confidence interval [CI]: 2 to 24) and antihistone antibodies (OR = 9.4; 95% CI: 4 to 26) were associated with the presence of proliferative glomerulonephritis. In the prospective study, 7 (6%) of the 121 patients developed proliferative lupus glomerulonephritis after a mean of 6 years of follow-up. Patients with initial antihistone (26% [5/19] vs. 2% [2/95], P = 0.0004) and anti-dsDNA reactivity (6% [2/33] vs. 0% [0/67], P = 0.048) had a greater risk of developing proliferative glomerulonephritis than patients without these autoantibodies. CONCLUSION: In addition to routine anti-dsDNA antibody assay, antihistone antibody measurement may be useful for identifying patients at increased risk of proliferative glomerulonephritis.