Characterisation of the rat oesophagus epithelium antigens defined by the so-called ''antikeratin antibodies'', specific for rheumatoid arthritis.

OBJECTIVES--An attempt was made to characterise the antigens recognised by serum IgG antibodies directed to the stratum corneum of rat oesophagus epithelium, the so-called 'antikeratin antibodies', which were shown to be highly specific for rheumatoid arthritis (RA) and thus to have an actual diagnostic value. METHODS--Immunoblotting was performed with RA serum samples on different extracts of rat oesophagus epithelium separated by various monodimensional and two dimensional electrophoreses. RESULTS--Three low-salt-soluble antigens sensitive to proteinase K and, therefore, of protein nature were identified. Two proteins, with apparent molecular masses of 210 and 120-90 kilodaltons, shared isoelectric points ranging from 5.8 to 8.5; the third protein exhibited isoelectric points from 4.5 to 7.2 while its molecular mass ranged from 130 to 60 kilodaltons. Immunoadsorption of RA serum samples onto cytokeratins extracted from the stratum corneum of rat oesophagus epithelium did not change their immunoreactivity towards the three antigenic proteins. Widely used deglycosylation and dephosphorylation methods failed to modify either the electrophoretic migration of the proteins or their immunoreactivity with RA serum samples. CONCLUSION--The so-called 'antikeratin antibodies' do not react with cytokeratins. They specifically recognise three late epithelial differentiation proteins which had not been previously described. These proteins may be related to (pro)filaggrin.     

Immunoblotting detection of so-called ''antikeratin antibodies'': a new assay for the diagnosis of rheumatoid arthritis.

OBJECTIVES--To assess the diagnostic value for rheumatoid arthritis (RA), of an immunoblotting assay based on the rat oesophagus epithelium antigens recognised by the so-called 'antikeratin antibodies' ('AKA'), antigens that have been identified as three non-cytokeratin proteins (referred to as A, B and C proteins). METHODS--After polyacrylamide gel electrophoresis in non-denaturing conditions and electrotransfer of an epithelial extract, the immunoreactivities to the A, B and C proteins of a series of serum samples from 88 patients with RA and 100 patients with non-rheumatoid rheumatic diseases, were semiquantitatively evaluated. RESULTS--A total of 81.8% of RA serum samples recognised the three proteins, while 91% of non-RA serum samples only weakly recognised the A and B proteins but not the C protein. Only in the group of RA patients, were the titres of the antibodies to the A, B and C proteins found to be significantly correlated with each other and with the titres of 'AKA' detected by the standard indirect immunofluorescence (IIF) method. For a diagnostic specificity of 99%, the diagnostic sensitivities of the detection of the A and B proteins were 50% and 43.2%, respectively, when those of the detection of 'AKA' by IIF and of IgM-rheumatoid factor by enzyme-linked immunosorbent assay were 42% and 54%, respectively. In contrast, at a same specificity of 99%, the diagnostic sensitivity of the detection of the C protein was significantly higher with a value of 70.5%. CONCLUSION--This immunoblotting assay which is the first immunochemical method proposed for the detection of 'AKA, should be validated on larger series of patients but can already be considered as a very powerful test for the serological diagnosis of RA.     

Significance of laminar antikeratin antibodies to rat oesophagus in rheumatoid arthritis.

Antikeratin antibodies reacting in a laminar distribution with keratinised rat oesophagus were found in the sera of a proportion of patients with rheumatoid arthritis but not in healthy controls. In rheumatoid arthritis (RA) the proportion of sera exhibiting this reactivity varied with the site tested in the rat's upper alimentary tract. There were 36.4% of 99 patients with RA who gave positive reactivity to the middle third of the rat oesophagus. This antikeratin reactivity was related to the occurrence of other antitissue antibodies (to reticulin, gastric parietal cells, smooth muscle, mitochondria, or nuclear components) in the same patients with rheumatoid arthritis. It was not related to the duration of early morning stiffness, the Ritchie index, the erythrocyte sedimentation rate, certain acute phase proteins (haptoglobin and C-reactive protein) nor to the levels of haemoglobin or immunoglobulins. Antikeratin antibodies were not specific for rheumatoid arthritis and also occurred in 50% of 16 patients with progressive systemic sclerosis.     

脱亚胺基重组鼠聚微丝蛋白抗体诊断类风湿关节炎的研究

目的评价脱亚胺基重组大鼠聚微丝蛋白抗体(ArFA)在类风湿关节炎(RA)诊断中的应用价值。方法分别测定了190例RA患者和150例其他患者的ArFA,以及196例RA患者和207例其他患者的抗环瓜氨酸肽(CCP)抗体,并分析了两种抗体诊断RA的敏感性、特异性、阴性预测值与阳性预测值。结果ArFA的敏感性、特异性、阳性预测值、阴性预测值分别为77.9%、93.3%、93.7%、76.9%;而抗CCP抗体的敏感性、特异性、阳性预测值、阴性预测值分别为67.9%、94.7%、92.4%、75.7%;ArFA的敏感性高于抗CCP抗体(P<0.05)。结论ArFA可作为RA诊断手段的补充,其较高的敏感性源于结构上的脱亚胺基。     

High diagnostic performance of ELISA detection of antibodies to citrullinated antigens in rheumatoid arthritis

OBJECTIVE: We investigated the rheumatoid arthritis (RA) diagnostic performances of anti-cyclic citrullinated peptide antibody (anti-CCP) and antifilaggrin antibody (AFA) in comparison with RF and matrix metalloproteinase-3 (MMP-3). METHODS: We used a second generation enzyme-linked immunosorbent assay (ELISA) kit for the detection of anti-CCP. We constructed recombinant human filaggrin, which was citrullinated in vitro by human peptidylarginine deiminase, and subsequently used it as the coating antigen for AFA-ELISA. A total of 549 RA patients and 208 other rheumatic disease patients were included in the study. RESULTS: The specificities of anti-CCP (88.9%) and AFA (94.7%) were superior to those of RF (81.7%) and MMP-3 (49.5%). The sensitivity of anti-CCP (87.6%) was superior to all others. However, the sensitivity of AFA (68.7%) was inferior to those of RF (69.8%) and MMP-3 (75.7%). Furthermore, receiver operating characteristic curves of anti-CCP and AFA passed closer to the upper left corner than those of RF and MMP-3, and the areas under the curves (AUC) of AFA and anti-CCP were significantly larger. In addition, the AUC of anti-CCP was significantly larger than that of AFA. CONCLUSION: ELISA detection of antibodies to citrullinated antigens, especially a second generation anti-CCP, showed higher discriminative ability than other assays, including RF, and would be useful to aid the diagnosis of RA in clinical practice.     

The value of the diagnostic criteria in rheumatoid arthritis

The ARA and the New York diagnostic criteria for rheumatoid arthritis were studied in 411 patients with a recent inflammatory joint disease (100 with RA, 311 with other disease) in order to evaluate their value in distinguishing progressive rheumatoid arthritis from other joint diseases. Rheumatoid factor, symmetrical polyarthritis, morning stiffness, and X-ray changes were of the greatest value in diagnosing RA in the early stage of the disease. Other diagnostic criteria had either a poor specificity or sensitivity, and were thus of less importance as discriminators.     

Diagnostic value of antikeratin antibodies in rheumatoid arthritis

The value of testing for antikeratin antibodies (AKA) in the diagnosis of rheumatic diseases was investigated. AKA were found in the serum of 71 (54%) of 131 patients with rheumatoid arthritis (RA) (including 10 rheumatoid factor (RF) negative individuals) but only in 7 (2%) of 266 patients with non-RA rheumatic diseases, in 2 (3%) of 69 patients with miscellaneous immunological diseases and in one of 100 healthy controls. AKA positivity in RA patients correlated with their age and the presence of RF, antinuclear antibodies, subcutaneous nodules, as well as the extent and severity of systemic disease manifestations. Our study suggests that determination of AKA would be of value in the assessment of patients suspected of having RA.     

抗聚角蛋白微丝蛋白抗体的检测在类风湿关节炎诊断中的意义

目的：探讨抗聚角蛋白微丝蛋白抗体（AFA）对RA诊断的意义，并比较其与抗核周因子抗体（APF），抗角蛋白抗体（AKA）以及HLA－DR4之间的相关性。方法；用免疫印迹法（WB）检测157例类风湿关节炎（RA）血清标本和104例对照血清，包括系统性红斑 狼疮（SLE)、干燥综合征（SS）、骨关节炎（OA）等的AFA。APF和AKA用间接免疫荧光法检测。结果：157例RA病人的AFA敏感性和特异性分别为36．3％、 93．4％，与疾病对照组和正常对照组相比，差异有显著性（P＜0．05）。57例AFA阳性的血清中，其中AKA同时阳性的有36例,重叠为63．2％；APF同时阳性的有38例，重叠率为66．7％；HLA－DR4同时阳性的有36例，重叠率为52．6％。统计学分析证实AFA与AKA、APF及HLA－DR4之间有相关性。结论：AFA对RA具有很高的特异性，可用于RA的临床诊断。AFA与APF、AKA及GLA－DR4有相关性。AFA不能完全替代APF和AKA，三项临床检测可互相补充,提高RA的诊断率。     

The diagnostic utilities of anti-agalactosyl IgG antibodies, anti-cyclic citrullinated peptide antibodies, and rheumatoid factors in rheumatoid arthritis

The purpose of this study was to investigate the diagnostic utilities of anti-agalactosyl IgG antibody (CARF), anti-cyclic citrullinated peptide (CCP) antibody and rheumatoid factor (RF) in rheumatoid arthritis (RA), non-RA rheumatic diseases, and chronic viral hepatitis. The authors determined serum levels of CARF and anti-CCP2 by ELISA and IgM-RF by a immunonephelometric method in 834 controls and in 397 patients with the following conditions: RA (100), non-RA rheumatic diseases [systemic lupus erythematosus (SLE) 30, primary Sjogren’s syndrome 18, systemic sclerosis 30, inflammatory myositis 19], chronic viral hepatitis B and C (HBV 100, HCV 100). The sensitivities of CARF (83%) and anti-CCP (85%) were significantly higher than that of RF (75%, p = 0.01, respectively) in RA, and the specificity of anti-CCP (98%) was significantly higher than those of CARF (92%) and RF (90%, p < 0.001, respectively). A comparison of receiver operating characteristic (ROC) curves revealed that the diagnostic accuracies of CARF and anti-CCP were superior to that of RF (CARF vs. RF, p = 0.008, anti-CCP vs. RF, p = 0.017) in RA. CARF positivity was significantly higher than those of anti-CCP (p = 0.007) and RF (p = 0.008) in systemic sclerosis, and the positivity of CARF was significantly higher than that of anti-CCP in Sjogren’s syndrome (p = 0.016). Furthermore, CARF had significantly higher positivity than anti-CCP or RF in chronic viral hepatitis B and C. Finally, the titers of these three markers in RA were significantly higher than in non-RA rheumatic diseases and in chronic viral hepatitis B and C. Our results suggest that anti-CCP is the most useful serologic marker for the differentiation of RA and non-RA rheumatic diseases, and chronic viral hepatitis B and C.     

Meta-analysis: diagnostic value of serum anti-mutated citrullinated vimentin antibodies in patients with rheumatoid arthritis

Conventional tests are not always helpful in making a diagnosis of rheumatoid arthritis (RA). This study aimed to comprehensively and quantitatively summarize the evidence on the accuracy of anti-mutated citrullinated vimentin (MCV) assay in the diagnosis of RA. A comprehensive meta-review of data on the accuracy of MCV concentrations in the diagnosis of RA were carried out from 16 published studies. Furthermore, receiver operating characteristic curves were used to summarize the overall test performance. The summary estimates for MCV in the diagnosis of RA were: sensitivity 0.77 [95% confidence interval (CI) 0.75–0.78], specificity 0.89 (95% CI 0.87–0.90), positive likelihood ratio (LR+) 7.24 (95% CI 5.60–9.36), negative likelihood ratio (LR−) 0.28 (95% CI 0.23–0.34) and diagnostic odds ratio 29.66 (95% CI 21.09–41.71). The area under the summary receiver operating characteristic curves was 0.92. Data from meta-analysis suggest the accuracy of MCV assay in the diagnosis of RA is high, but ultimately clinician must consider the results of MCV tests combing with other conventional examinations and the clinical feature.     

Discriminative and diagnostic value of anti-cyclic citrullinated peptide antibodies in Iranian patients with rheumatoid arthritis

Most studies on the diagnostic utility of the anti-cyclic citrullinated peptide antibody (anti-CCP) test in rheumatoid arthritis (RA) have been performed in developed countries, with only a few done in the developing world. We undertook a cross-sectional study to determine the diagnostic utility of the rheumatoid factor (RF) and anti-CCP tests in urbanized Iranians with early RA. One hundred and ninety-three serum samples were obtained from consecutive patients who were diagnosed with RA. Serum samples of 254 ones without RA, consisting of other inflammatory polyarthritis disorders, were also collected as controls. RF was measured for IgM by latex agglutination test, and titers higher than 1/80 were considered positive. Anti-CCP was also assayed using an ELISA with 6.25 RU/ml as the threshold for a positive result. The anti-CCP had sensitivity, specificity, positive predictive value, and negative predictive value for a diagnosis of RA of 47.2, 92.9, 83.5, and 69.8 %, respectively. Those for RF were 57.0, 83.9, 72.8, and 72.0 %, respectively. For anti-CCP antibodies in combination with RF, they were 38.9, 96.5, 89.3, and 67.5 %, respectively. Anti-CCP has higher specificity and predictive values compared with the RF parameter in diagnosing RA in Iranian patients, but their discriminative values were similar. Anti-CCP and RF in combination further increases the diagnostic value for RA.     

抗CB10抗体在类风湿关节炎患者中的意义

目的检测抗Ⅱ型胶原抗原表位的多肽片段（GPAGTAGAR）抗体，即抗CB10抗体在类风湿关节炎（RA）中的阳性率，探讨抗CB10抗体在RA中的意义。方法以人工合成CB10多肽为抗原，用酶联免疫吸附试验（ELISA）检测164例RA、40例系统性红斑狼疮（SLE）、55例骨关节炎（OA）、66例强直性脊柱炎（AS）、63名正常人血清及19例RA和14例AS关节液中抗CB10抗体的水平。分析比较各组抗CB10抗体的水平及其与临床资料的关系。结果RA患者血清中抗CB10抗体的吸光度（A）值水平明显高于其他风湿病组和正常对照组，差异有统计学意义（P〈0．01），其在RA、SLE、AS、OA及正常对照组中的阳性率分别为：71．3％、12．5％、30．3％、12、7％和3．2％，对RA的敏感性为71．3％，特异性为82．1％；阳性预测值为77．5％，阴性预测值为80．2％。病程≤2年的RA患者抗CB10抗体阳性率明显高于病程〉2年者，差异有统计学意义（P〈0．05）。抗CB10抗体与病程及x线分期呈负相关（P〈0．05），与关节压痛数、关节肿胀数、晨僵、休息痛、健康评价问卷（HAQ）、类风湿因子（RF）、抗环瓜氨酸肽（CCP）抗体、红细胞沉降率（ESR）等指标无明显相关性。结论RA患者血清中抗CB10抗体明显升高，对RA诊断有较好的敏感性和特异性：抗CB10抗体与病程及x线分期呈负相关。     

Diagnostic value of antiagalactosyl IgG antibodies in rheumatoid arthritis

Our objective in this study was to explore the diagnostic value of antiagalactosyl IgG antibodies in rheumatoid arthritis (RA). The study comprised 266 Japanese patients with systemic autoimmune diseases, including 60 with RA. Human agalactosyl IgG was prepared enzymatically, and the serum levels of antiagalactosyl IgG antibodies were determined using a lectin enzyme immunoassay. Serum IgG and IgM rheumatoid factors (RF) were measured using laser nephelometry for IgM (LN-RF) and an enzyme-linked immunosorbent assay for IgG (IgG-RF). Antiagalactosyl IgG antibodies were significantly more common in patients with RA than in those without (78% vs. 18%, odds ratio (OR) 16.51, 95% confidence interval (CI) 8.12–33.58, p<0.0001). Patients with RA also had a higher frequency of LN-RF than those without RA (75% vs. 28%, OR 7.81, 95% CI 3.91–15.58, p< 0.001). The specificity of antiagalactosyl IgG antibodies for RA was significantly higher than that of LN-RF (82% vs. 72%, p<0.0011). There was a significant correlation between titers of antiagalactosyl IgG antibodies and C-reactive protein levels. Antiagalactosyl IgG antibodies are more specific markers for RA than conventional LN-RF, and may provide useful information for the diagnosis of RA.Abbreviations AKA Antikeratin antibodies - RA Rheumatoid arthritis - RF Rheumatoid factor - SLE Systemic lupus erythematosus     

抗环瓜氨酸肽抗体和葡萄糖-6-磷酸-异构酶抗原对类风湿关节炎诊断价值的比较

目的评价抗环瓜氨酸肽（CCP）抗体和葡萄糖-6-磷酸-异构酶（GPI）抗原对类风湿关节炎（RA）的诊断价值。方法用酶联免疫吸附试验（ELISA）法分别测定RA患者112例、非RA其他风湿病患者44例以及健康志愿者119名血清中的抗CCP抗体、GPI抗原和IgM—RF，应用ROC比较抗CCP抗体和GPI抗原对RA的诊断价值，用Spearman方法分析上述指标与lgM—RF的相关性。结果在诊断RA时．抗CCP抗体和GPI抗原的ROC曲线下面积均大于IgM—RF（P均〈0．05）。抗CCP抗体、GPI抗原与IgM—RF显著相关。CCP抗体与GPI抗原的联合试验的灵敏度达到0．946。结论联合测定抗CCP抗体和GPI抗原对RA具有较高的诊断价值，具有良好的应用前景。     

The prognostic value of the antiperinuclear factor, anti-citrullinated peptide antibodies and rheumatoid factor in early rheumatoid arthritis

OBJECTIVE: To study the prognostic value of the antiperinuclear factor (APF), determined by an indirect immunofluorescence test (IIF) and a recently developed anti-citrullinated cyclic peptide (CCP) ELISA, in combination with rheumatoid factor (RF) status, in early RA (< 1 year). METHODS: A total of 249 participants in a randomized trial of treatment strategies were divided into 4 groups according to their APF (or CCP) and RF status at baseline. Differences in disability, joint involvement and radiological damage over a 3-year period were analysed. RESULTS: APF-IIF results differed from CCP-ELISA in 42 cases (17%); 38 of the 42 had a positive IIF and negative ELISA value. Disability after 3 years did not differ significantly between the RF and APF groups. APF- patients had significantly lower Thompson joint scores compared to APF+ patients (6 vs 24 for CCP-ELISA; 2 vs 24 for IIF). RF+APF+ patients exhibited more radiological damage compared to RF-APF- patients. RF+APF- and RF-APF+ patients had intermediate scores. Within the RF+ and RF- groups, APF+ was associated with more radiological damage and thus yielded prognostic information in addition to RF. In this respect, the results of ELISA and IIF were comparable. Thirty percent of the RF+APF+ patients had a radiological score higher than 45, compared to 13% of the RF+APF-, none of the RF-APF+, and 2% of RF-APF- patients (p < 0.001). In addition, more large joints were affected in APF+ than in APF- patients, while no difference was observed between RF+ and RF- patients. CONCLUSION: APF has prognostic value in addition to RF for joint involvement and radiological damage in early RA. The CCP-ELISA technique for APF assessment may facilitate its use in clinical practice. However, the prognostic value of the two tests lies in their ability to predict mild disease. Reliable identification at baseline of individual patients with progressive disease is still not possible.