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。     

系统性红斑狼疮患者血清抗核小体抗体检测分析

目的探讨血清抗核小体抗体（ANuA）的检测在系统性红斑狼疮（SLE）患者中的意义。方法采用免疫印迹法检测58例SLE患者及40例健康人血清抗核小体抗体。结果SLE患者血清ANuA阳性率为74．1％。SLE患者与健康对照组血清中ANuA阳性率差异具有极显著性（P〈0．001）。SLE活动期患者与非活动期患者ANuA阳性率差异有极显著性（P〈0．001）。结论ANuA可以作为抗dsDNA和抗Sm以外的诊断SLE和判断SLE活动期的一种新的自身抗体。     

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。     

SmD1抗体检测在系统性红斑狼疮诊断中的意义

目的 研究抗SmD1抗体及其他特异性抗体在系统性红斑狼疮（SLE）诊断中的意义。方法 测定了44例SLE及136例非SEE（包括干燥综合征、未分化结缔组织病、强直性脊柱炎、类风湿关节炎）患者血清中的自身抗体。利用免疫印迹法测定抗SmD1抗体、抗核小体抗体（ANuA）和抗SSA60000抗体，间接免疫荧光法测定抗核抗体（ANA）和抗双链DNA（dsDNA）抗体．免疫斑点法检测抗Sm抗体。结果 抗SmD1抗体在SLE患者中的阳性率为47.7％，高于抗Sm抗体阳性率18．2％，差异有统计学意义（P〈0．05），而且其抗SmD1抗体的特异性达97.1％。结论 抗SmD1抗体在狼疮的诊断中有很高的特异性，敏感性也高于抗Sm抗体。5种特异性抗体在SLE诊断中有明显的互补作用，联合检测可明显提高其对SLE诊断的敏感性。     

系统性红斑狼疮患者C1q受体和C1q抗体的表达及其与发病相关性的研究

目的 检测系统性红斑狼疮（SEE）患者外周血单个核细胞C1qRp和gC1qR的表达及与C1q抗体、补体C1q水平的关系，并进一步探讨其在SLE发病中的意义。方法 用流式细胞计数法测定58例SLE和30名正常人外周血中性粒细胞、单核细胞、淋巴细胞的C1qRp和gc1qR的表达，同时测血清C1q抗体、C1q水平．并将其与C3、c4、抗核抗体（ANA）、抗dsDNA抗体、SLEDAI积分做相关性分析。结果 SLE患者外周血中性粒细胞、单核细胞的C1qRp表达为（7．2±2-3）％和（3．4±2．1）％，均较正常人[（10．6±2．1）％和（9．0±8．7）％]降低（P〈0．05），淋巴细胞不表达C1qRp，但可表达gC1qR。C1qRp在SLE活动期表达略低于稳定期，但差异无统计学意义。SLE患者的gC1qR表达略高于正常人．gC1qR在活动期高于稳定期，但差异无统计学意义。SLE患者血清C1q抗体水平（98±41）U／ml，明显高于正常，C1q为（0．13±0．08）dE，低于正常值。外周血单个核细胞的C1qRp表达与血清C1qAb水平（Pearsonr=-0．574，P〈0．05）、双链DNA（ds—DNA）抗体滴度呈负相关，与补体C1q（Pearsonr=0．673．P〈0．01）、C3、C4水平呈正相关。gc1qR与C1qAb和补体C1q无明显相关性。结论 SLE患者外周血中性粒细胞、单个核细胞C1qR的表达缺陷，导致SLE吞噬功能受损，凋亡细胞清除障碍，诱导产生自身抗体，在SLE的免疫发病机制中起重要的作用。     

抗核小体抗体诊断系统性红斑狼疮的价值

280份血清,取自健康体检者50例，类风湿关节炎（RA）74例，系统性红斑狼疮（SLE）106例．其他结缔组织病50例．分别检测其抗核抗体（ANA），抗双链DNA（dsDNA），抗史密斯（Sm），抗组蛋白（His）及抗核小体抗体（AnuA）抗体。结果5种抗体诊断SLE的敏感性和特异性为；ANA96．2%、31％，AnuA80．1％、93％，dsDNA56．6%、92％，Sm49．7％、90％，His54．7％、85%。ANA、AnuA敏感性明显高于其他3种抗体（P〈0．001）．AnuA、dsDNA、HiS、Sm的特异性明显高于ANA（P〈0．001）。AnuA是SLE的又一种特异性抗体，其与ANA、dsDNA抗体及Sm抗体、His抗体联合检测对SLE的诊断有重要意义。     

系统性红斑狼疮血清抗核小体抗体水平及意义的探讨

目的 研究抗核小体抗体(AnuA)在系统性红斑狼疮(systemic lupus erythematosus，SLE)患者血清中的水平及其相关影响因素，探讨AnuA在SLE诊治中的作用和意义。方法 采用酶联免疫吸附法(EUSA)测定120例初诊SLE患者、55例其他风湿性疾病和30名健康对照血清中AnuA水平。同时记录各种临床表现，检测并分析其治疗前的其他自身抗体和实验室指标。结果 自身抗体在SLE及其他风湿病对照组的阳性率分别为AnuA56％和7％，抗dsDNA抗体35％和1％，抗Sm抗体24％和0。AnuA与SLE患者性别、年龄、病程无相关性，对sLE的诊断敏感性和特异性分别为55．8％、9513％，对狼疮肾炎(1upus nephritis，LN)的诊断敏感性和特异性分别为77．％、64．5%。AnuA与肝脏损害和疾病活动呈线性相关(t=3．152，2．171，P＜O．05)。AnuA分别与抗dsDNA、抗Sm联合检测对SLE诊断敏感性提高27％、40％（X^2值分别为38．930、18．161，P＜O．01)。结论AnuA在SLE血清中水平显著增高，AnuA测定是SLE诊断和治疗监测中有价值的新的实验室检测指标之一，与抗dsDNA抗体联合检测可提高诊断SLE、LN的敏感性和特异性。     

补体C1q及抗C1q抗体与系统性红斑狼疮及狼疮肾炎相关性的研究

目的 检测系统性红斑狼疮（SLE）患者血清补体C1q及抗C1q抗体（C1qAb）水平，比较血清C1q与C1qAb之间的相关性；分析血清C1q及C1qAb水平与SLE、狼疮肾炎（LN）以及SLE病情活动的相关性。方法 采用单向免疫扩散法（SRID）检测血清C1q，酶联免疫吸附法（ELISA）检测血清C1qAb。结果 SLE患者的血清C1q水平显著低于其他对照组，而血清C1qAb水平显著高于其他对照组。其中LN患者的血清C1q水平显著低于非LN的SLE患者、血清C1qAb水平显著高于非LN的SLE患者。SLE患者血清C1qAb与C1q之间呈显著负相关。病情活动期的SLE患者血清C1q水平显著低于稳定期患者；血清C1qAb水平显著高于稳定期患者。结论 血清C1q的降低及血清C1qAb的升高与SLE相关。血清C1qAb的升高，可能是导致血清C1q降低的主要原因之一。血清C1q、C1qAb水平与SLE患者肾脏损害显著相关。血清C1q、C1qAb水平与病情活动显著相关。     

抗细胞膜DNA自身抗体快速检测系统性红斑狼疮

目的 探讨抗细胞膜DNA自身抗体（mDNA)在系统性红斑狼疮患者的表达以及这种特异抗体与抗dsDNA抗体的不同。方法 用间接免疫荧光法观察培养的HL60细胞的特异性细胞膜的荧光图形。结果 抗细胞膜DNA自身抗体在SLE患者90例中有81例阳性（阳性率90％）,而在类风湿关节炎（RA）患者35例,强直性脊柱炎（AS）患者31例和健康献血员42名中均为阴性,在干燥综合征（SS）患者20例中有1例阳性（阳性率5％）,抗细胞膜DNA自身抗体对SLE诊断的特异性为98．8％。结论 抗细胞膜DNA自身抗体是一种诊断。SLE的新的标记抗体,其敏感性高（90．0％）,特异性强（98．8％）,较抗dsDNA抗体、抗Sm抗体检测更先进。     

Anti-nucleosome antibodies: A potential surrogate marker for renal affection in lupus patients with insignificant proteinuria

BackgroundLupus nephritis (LN) is a serious manifestation of systemic lupus erythematosus (SLE). Clinical renal involvement is present in about two-thirds of lupus patients and more patients would have morphologic evidence of renal disease without clinical manifestations.Aim of the workTo investigate serum anti-nucleosome antibodies role as a biomarker for renal affection in lupus patients with insignificant proteinuria.Patients and methodsTwenty-four lupus patients with proteinuria <500 mg/d (group-A), 30 patients with established lupus nephritis (group-B) and 15 controls were included. Systemic lupus erythematosis disease activity index (SLEDAI), anti-nucleosome, anti-dsDNA antibodies and renal biopsy were assessed in all patients.ResultsSerum anti-nucleosome antibodies were significantly higher in all lupus patients than control (P < 0.001) and showed significant positive correlation with SLEDAI score. SLE patients with positive anti-dsDNA antibody had more active disease by SLEDAI and higher levels of anti-nucleosome antibodies than those with negative anti-dsDNA antibodies. In both studied groups, serum anti-nucleosome antibodies were significantly higher in patients with class II LN than the control and in class III LN than in class II LN (P < 0.001). Yet, in both groups, anti-nucleosome was not useful in differentiating active from chronic renal affection.ConclusionSerum levels of anti-nucleosome antibodies are associated with active lupus disease and correlate with the degree of renal affection. In patients with insignificant proteinuria, serum levels of anti-nucleosome antibodies were elevated and were related to the degree of renal affection. Anti-nucleosome antibodies may be used as a surrogate marker for early renal affection in lupus patients with insignificant proteinuria.     

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.     

Anti-nucleosome antibodies may predict lupus nephritis and severity of disease in systemic lupus erythematosus

Background/ObjectiveDetection of anti-nucleosome antibodies in patients with systemic lupus erythematosus (SLE) has been well established and it is claimed that their presence is associated with disease activity. The objective of this study is to determine the diagnostic value of anti-nucleosome antibodies in the assessment of lupus nephritis and clinically active SLE.MethodsThe anti-nucleosome antibodies were evaluated in the serum of 200 Tunisian SLE patients at disease onset by a sensitive immunodot assay. Serum samples from each patient were also tested for ANA and anti-ds DNA antibody by IIF on Hep 2 cells and Crithidia luciliae respectively. During the follow-up, the patients were regularly monitored for clinical parameters. Global SLE activity was measured by the European Consensus Lupus Activity Measurement (ECLAM).ResultsThe prevalence of anti-nucleosome and anti-dsDNA antibodies was 69% and 63.5% respectively. Anti-nucleosome antibodies were found to be 30.1% positive in SLE patients lacking anti-dsDNA antibody. 79.5% patients had active SLE at the first clinical examination. Anti-nucleosome antibodies were more sensitive than anti-dsDNA antibodies to detect active SLE (78% vs. 71.7%, P =0.19). 52.5% of SLE patients had renal involvement. Among these patients, the rate of anti-nucleosome positivity and anti-dsDNA were 77.1% and 67.6% respectively. The positivity of anti-nucleosome antibodies was significantly higher in patients with renal disease than the subjects without renal disease (P = 0.009). Anti-nucleosome and anti-ds DNA antibodies were significantly correlated with disease activity (P < 0.001 and P < 0.001 respectively).ConclusionAnti-nucleosome antibody reactivity may be a useful marker in the diagnosis and assessment of active SLE.     

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.     

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.     

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.