Anti-cyclic citrullinated peptide antibody in systemic sclerosis

OBJECTIVES:To determine if anti-cyclic citrullinated peptide (anti-CCP) antibody titers can distinguish the overlap syndrome of systemic sclerosis and rheumatoid arthritis (SSc-RA) in patients with systemic sclerosis (SSc) and to investigate the clinical significance of anti-CCP antibodies in SSc.METHODS:Serum levels of anti-CCP antibodies were measured by enzyme-linked immunosorbent assay in 159 outpatients: 114 with SSc, 14 with rheumatoid arthritis, 7 with SSc-RA overlap syndrome, and 24 with Sj?gren's syndrome. In patients with SSc and SSc-RA, we also measured serum levels of matrix metalloproteinase-3 and anti-agalactosyl IgG antibody.RESULTS:Elevated serum levels of anti-CCP antibodies were observed in 3 of 114 patients (2.6%) with SSc, 9 of 14 patients (64%) with RA, 6 of 7 patients (86%) with SSc-RA, and only 1 of 24 patients (4.2%) with SjS. In patients with SSc-RA, serum anti-CCP antibody levels were significantly higher than those seen in SSc (p<0.001). The sensitivity, specificity, and predictive values of elevated anti-CCP titers for SSc-RA were higher than either matrix metalloproteinase-3 and anti-agalactosyl IgG antibodies as markers. In addition, almost all SSc-RA and SSc patients with elevated serum levels of anti-CCP antibodies exhibited arthralgias and interstitial pneumonia.CONCLUSIONS:Anti-CCP antibody titers are a reliable marker of SSc-RA facilitating its distinction from SSc alone.     

Anti-cyclic citrullinated peptide antibody isotypes in rheumatoid arthritis: association with disease duration, rheumatoid factor production and the presence of shared epitope

OBJECTIVE: Anti-cyclic citrullinated peptide (anti-CCP) antibodies of IgG isotype are specific diagnostic markers of rheumatoid arthritis (RA). Recent evidence also points to their direct involvement in the pathophysiology. Little information is available, however, regarding the isotype distribution of anti-CCP antibodies and the characteristics of IgA and IgM anti-CCP. METHODS: IgG, IgA and IgM anti-CCP2 and rheumatoid factor (RF) levels were measured in the sera of 119 RA patients and 118 controls, including patients with other rheumatic diseases and healthy subjects. We analyzed the diagnostic performance of IgA and IgM anti-CCP2 antibodies and their relationship with IgG anti-CCP2, RFs, disease duration and the presence of HLA-DRB1 shared epitope (SE) alleles. RESULTS: Patients with RA had significantly higher serum IgA and IgM anti-CCP2 antibody levels than healthy subjects and patients with other rheumatic diseases (p<0.0001). IgG, IgA and IgM anti-CCP2 antibodies were present in 74.8%, 52.9% and 44.5% of RA patients, and their diagnostic specificity was 95.8%, 95.8% and 91.6%, respectively. The presence of anti-CCP2 antibodies was significantly associated with SE alleles (p=0.03). The frequency of IgM anti-CCP2 positivity was lower in longstanding disease compared to early RA (p=0.03). CONCLUSION: IgA and IgM anti-CCP2 antibodies are present in RA patients, and they are similarly specific for RA as IgG anti-CCP2. The higher frequency of IgM anti-CCP2 antibodies in early RA suggests that they are mostly generated during the first phase of immune response; nonetheless, their production seems to be sustained in some patients. Further analysis of IgM and IgA anti-CCP2 antibodies may provide insights into the pathogenesis of RA.     

Autoantibodies to cyclic citrullinated peptide 2 (CCP2) are superior to other potential diagnostic biomarkers for predicting rheumatoid arthritis in early undifferentiated arthritis

We evaluated the diagnostic value of anti-cyclic citrullinated peptide 2 (anti-CCP2) antibodies and other potential diagnostic biomarkers (IgM rheumatoid factor, anti-agalactosyl IgG antibodies, matrix metalloproteinase 3, C-reactive protein) for predicting early development of rheumatoid arthritis (RA). Patients were defined as having recent-onset undifferentiated arthritis (UA) if they had developed arthritis in two or more joints within the previous 2 years and could not be classified with a well-defined arthropathy. Baseline levels of biomarkers were measured in blood samples collected at the entry of the study and the patients were followed for 1 year to monitor development of RA. Diagnoses of RA and non-RA arthropathies were made according to individual standard diagnostic criteria. A total of 146 patients were enrolled in the study. In the follow-up year, 18 patients developed RA, 54 developed non-RA arthropathies, and 60 remained in the UA category. The sensitivity and specificity of the presence of anti-CCP2 antibodies for the diagnosis of RA were 83.3 and 93.0%, respectively. The positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of anti-CCP2 antibodies for RA (65.2, 97.2, and 91.7%, respectively) were higher than for any other biomarker. Combination of anti-CCP2 with any other biomarker only slightly improved each diagnostic value compared to the presence of anti-CCP2 alone. Among the anti-CCP2-positive patients, the average titer was significantly higher in those with RA than in non-RA or UA patients (163.7 +/- 138.4 vs 55.2 +/- 72.0 U/ml, p = 0.017). Anti-CCP2 antibodies are superior to any other single biomarker for predicting early development of RA in patients with recent-onset UA and the diagnostic value of anti-CCP2 alone is similar to that for biomarker combinations. Moreover, the anti-CCP2 antibody titer is useful to discriminate between patients at high risk for early developing RA from those at risk of developing non-RA arthropathies.     

Diagnostic value of anti-cyclic citrullinated peptide antibodies in northern Chinese Han patients with rheumatoid arthritis and its correlation with disease activity

This study was to evaluate the diagnostic value of anti-cyclic citrullinated peptide (CCP) antibodies in northern Chinese Han patients with rheumatoid arthritis (RA) and its correlation with disease activity. Clinical data and serum samples were collected from 112 RA patients and 55 non-RA patients. Statistical analyses of the correlations among anti-CCP antibodies, other serological markers, and the RA patients’ clinical characteristics were performed using SPSS 11.5 software. Anti-CCP antibodies were detected in 77.7% of all RA patients and 80.4% of the RA patients with a disease duration of 3 years or less. The combined diagnosis using high titer anti-CCP antibodies (≥100 RU/ml) with a concomitant positive rheumatoid factor (RF) test exhibited the greatest diagnostic specificity; it achieved 87.9% for all RA patients and 90.1% for the patients with disease duration of three years or less. Moreover, anti-CCP antibodies showed medium correlations to the RA patient’s serum RF titer (r?=?0.560, P?<?0.001) and disease activity (DAS28 score; r?=?0.404, P?<?0.001). Compared with the patients with low anti-CCP antibody titers (<100 RU/ml), patients with high anti-CCP antibody titers showed higher RF titers, worse DAS28 scores, and severe morning stiffness (P?<?0.01). This study suggests that anti-CCP antibodies can be used for RA diagnosis and disease activity evaluation for northern Han Chinese patients. A combined diagnosis using both high titers of anti-CCP antibodies (≥100 RU/ml) and a positive RF test markedly improves RA diagnostic specificity. Patients’ DAS28 scores rise and morning stiffness intensifies with increasing anti-CCP antibody titers.     

The predictive value of rheumatoid factor isotypes, anti-cyclic citrullinated peptide antibodies, and antineutrophil cytoplasmic antibodies for mortality in patients with rheumatoid arthritis

OBJECTIVE: To evaluate the significance of rheumatoid factor (RF) and its isotypes (IgA RF, IgG RF, and IgM RF), anti-cyclic citrullinated peptide antibodies (anti-CCP), and antineutrophil cytoplasmic antibodies (ANCA) in predicting mortality in patients with rheumatoid arthritis (RA). METHODS: The study population comprised 604 patients with RA participating in a cross-sectional study in 1987. Presence of RF (n = 604), RF isotypes (n = 206), anti-CCP (n = 184), and ANCA (n = 200) were determined in these patients from available baseline sera. Vital status was assessed in 1999 and multivariate Cox regression analysis used to compare mortality in RA patients with or without different antibodies. RESULTS: Of the 604 patients with RA, 55% were positive for RF, 66% for anti-CCP, and 14.5% for perinuclear ANCA. Twelve patients (19%) with RF were anti-CCP-negative and 34 (40%) without RF were anti-CCP-positive. Of the total 604 patients, 160 had died by 1999. Positive RF and high IgA and IgM RF levels predicted increased mortality, while positive anti-CCP or ANCA did not. However, high anti-CCP levels were related to an increased mortality risk. CONCLUSION: Patients with RA with positive RF, especially IgA and IgM isotypes, carry a risk of dying earlier than patients without these serological findings.     

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.     

Anti-cyclic citrullinated peptide antibodies as a discriminating marker between rheumatoid arthritis and chronic hepatitis C-related polyarthropathy

Articular involvement is a frequent extrahepatic manifestation of hepatitis C virus (HCV) infection. The distinction between HCV-related polyarthropathy and true RA may be very difficult, especially with recent onset RA before articular damage and erosions develop. The objective of the study is to assess the diagnostic utility of anti-CCP antibodies and compare it with that of rheumatoid factor (RF) in distinguishing between rheumatoid arthritis (RA) and HCV-related polyarthropathy. Anti-cyclic citrullinated peptide (CCP) antibodies and RF were determined in the sera of 30 patients with RA and 22 patients with HCV-related polyarthropathy. Anti-CCP antibodies were positive in 83.3% of patients with RA and in 4.5% in patients with HCV and polyarthropathy. RF was positive in 90% of RA patients and in 81.1% of HCV patients with polyarthropathy. The anti-CCP antibodies showed higher specificity for RA compared with RF (95.4 vs. 18.2%). However, the sensitivity of anti-CCP was comparable to that of RF (83.3 vs. 90%). In conclusions, anti-CCP antibodies are reliable laboratory markers to differentiate between RA and HCV-related polyarthropathy.     

类风湿关节炎中抗纤聚蛋白抗体意义的探讨

目的探讨抗纤聚蛋白抗体(AFA)在类风湿关节炎(RA)中的意义,并比较AFA与类风湿因子(RF)、抗角蛋白抗体(AKA)、抗核周因子(APF)和抗环瓜氨酸肽(CCP)抗体以及某些临床指标的相关性。方法对860例研究对象,包括388例RA患者(其中早期172例,中晚期216例),422例非RA的风湿性疾病患者,50名健康对照,用免疫印迹法(IB)检测血清中的AFA。同时检测其他RA相关自身抗体。结果AFA在早期RA病例中阳性率为62.2%,在中晚期RA病例中阳性率为58.8%,对RA诊断敏感性60.3%,特异性91.1%,阳性和阴性预测值分别为94.6%、68.0%。AFA和AKA在早期和中晚期RA的阳性率差异无统计学意义,而RF、APF和抗CCP抗体在中晚期组的阳性率大于早期组。AFA与RF、AKA、APF以及抗CCP抗体相关(P<0.05)。AFA与RA患者平均发病年龄相关(P=0.047)。结论AFA可视为RA的特异性血清学标记,尤其对RF阴性及早期RA诊断很有帮助;AFA与其他RA相关自身抗体相关,联合检测可以相互补充,提高对RA的诊断。     

Anti-agalactosyl IgG antibodies in Thai patients with rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis

This study was performed to determine the prevalence of anti-agalactosyl IgG antibodies in Thai patients with RA, systemic lupus erythematosus (SLE) and systemic sclerosis (SSc), and determine the sensitivity and specificity of anti-agalactosyl IgG antibodies in the diagnosis of RA in comparison with IgM-rheumatoid factor (IgM-RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies. Serum samples were obtained from 100 patients with RA, 50 cases of SLE, 50 cases of SSc, and 100 healthy controls and analyzed for the presence of anti-agalactosyl IgG antibodies, IgM-RF and anti-CCP antibodies. A serum value greater than mean + 2 standard deviation of normal value of anti-agalactosyl IgG antibodies and anti-CCP antibodies was considered positive. The prevalence of anti-agalactosyl IgG antibodies in RA, SLE, and SSc patients was 88.0%, 14.0%, and 12.0%, respectively. The serum level of anti-agalactosyl IgG antibodies in patients with RA (227.10 ± 353.64 AU/mL) was significantly higher than those in SLE (11.84 ± 52.04 AU/mL), SSc (18.85 ± 99.60 AU/mL), and healthy controls (2.14 ± 1.97 AU/mL), (p < 0.001). There was a good correlation between the log serum level of anti-agalactosyl IgG antibodies and IgM-RF (r = 0.92, p < 0.001), anti-CCP antibodies and IgM-RF (r = 0.49, p < 0.001), and anti-agalactosyl IgG antibodies and anti-CCP antibodies (r = 0.55, p < 0.001). The sensitivity and specificity in the diagnosis of RA was 88.00% and 96.00% for anti-agalactosyl IgG antibodies, 90.00% and 99.00% for anti-CCP antibodies, and 91.00% and 95.00% for IgM-RF, respectively. The serum level of anti-agalactosyl IgG antibodies was significantly higher in RA than in SLE, SSc, and healthy controls. There was a good correlation between serum levels of anti-agalactosyl IgG antibodies, anti-CCP antibodies, and IgM-RF. These three tests had comparable sensitivity and specificity.     

The diagnostic utility of matrix metalloproteinase-3 and high-sensitivity C-reactive protein for predicting rheumatoid arthritis in anti-cyclic citrullinated peptide antibody-negative patients with recent-onset undifferentiated arthritis

Anti-cyclic citrullinated peptide (anti-CCP) antibodies are well-established serological markers that show high sensitivity and specificity in early rheumatoid arthritis (RA) and are associated with bone erosions of RA. However, some patients subsequently progress to RA even if there is no presence of anti-CCP antibodies in an early stage. The aim of this study is to evaluate the diagnostic utility of matrix metalloproteinase-3 (MMP-3), high-sensitivity C-reactive protein (hsCRP) and IgM rheumatoid factor for predicting RA in anti-CCP-negative patients with recent-onset undifferentiated arthritis (UA). Baseline levels of those markers were measured at the entry of the study. A total of 99 patients with UA were included, among them 44 patients (44.4 %) had been classified as having RA by a skilled rheumatologist at some point during 1-year follow-up. Of these 99 patients, 34 patients (34.3 %) had anti-CCP antibodies and 65 patients (65.7 %) had no anti-CCP antibodies. Eleven patients who were anti-CCP-negative developed RA. We compared sensitivity, specificity, positive predictive value and negative predictive value of serum markers of these anti-CCP-negative RA patients. The combined usage of MMP-3 with hsCRP is relatively superior to other markers as predictors of RA.     

血清葡萄糖6-磷酸异构酶抗原、类风湿因子和第2代抗环瓜氨酸肽抗体对类风湿关节炎诊断价值的比较

目的 检测葡萄糖6-磷酸异构酶（glucose-6-phosphate isomerase,GPI）抗原在类风湿关节炎（rheumatoid arthritis,RA）中的表达情况,并比较其与类风湿因子（rheumatoid factor,RF）和第2代抗环瓜氨酸肽（the second generation of anti-cyclic citrullinated peptide,抗CCP2）抗体对RA的诊断价值.方法 采用酶联免疫吸附试验检测126例RA和122例非RA患者血清GPI抗原和抗CCP2抗体,速率散射比浊法检测RF.结果 血清GPI浓度在RA患者较非RA组显著增高,差异有统计学意义[（0.28±0.65） mg/L vs.（0.07±0.36） mg/L,P〈0.005].GPI对RA的诊断敏感性为32.5%,低于RF（69.0%）和抗CCP2抗体（72.2%）的诊断敏感性,差异均有显著统计学意义（P〈0.001）;GPI、RF和抗CCP2抗体对RA的诊断特异性分别为89.3%、87.7%和95.1%,差异无显著统计学意义（P〉0.05）.与单一检测抗CCP2抗体比较,GPI及RF同时阳性、GPI及抗CCP2抗体同时阳性、以及GPI、RF及抗CCP2抗体三项同时阳性的诊断敏感性降低;而GPI或RF、GPI或抗CCP2、以及GPI或RF或抗CCP2单一阳性的诊断特异性降低,均有显著统计学意义（P＜0.05）.结论 血清GPI对RA诊断的敏感性低,可与高敏感性的抗CCP2抗体联合检测.     

The presence of anti-citrullinated protein antibodies (ACPA) and rheumatoid factor on patients with rheumatoid arthritis (RA) does not interfere with the chance of clinical remission in a follow-up of 3?years

Autoantibodies in early rheumatoid arthritis (RA) have important diagnostic value. The association between the presence of autoantibodies against cyclic citrullinated peptide and the response to treatment is controversial. To prospectively evaluate a cohort of patients with early rheumatoid arthritis (<12?months of symptoms) in order to determine the association between serological markers (rheumatoid factor (RF), anti-citrullinated protein antibodies) such as anti-cyclic citrullinated peptide antibodies (anti-CCP) and citrullinated anti-vimentin (anti-Sa) with the occurrence of clinical remission, forty patients diagnosed with early RA at the time of diagnosis were evaluated and followed for 3?years, in use of standardized therapeutic treatment. Demographic and clinical data were recorded, disease activity score 28 (DAS 28), as well as serology tests (ELISA) for RF (IgM, IgG, and IgA), anti-CCP (CCP2, CCP3, and CCP3.1) and anti-Sa in the initial evaluation and at 3, 6, 12, 18, 24, and 36?months of follow-up. The outcome evaluated was the percentage of patients with clinical remission, which was defined by DAS 28 lower than 2.6. Comparisons were made through the Student t test, mixed-effects regression analysis, and analysis of variance (significance level of 5%). The mean age was 45?years, and a female predominance was observed (90%). At the time of diagnosis, RF was observed in 50% of cases (RF IgA??42%, RF IgG??30%, and RF IgM??50%), anti-CCP in 50% (no difference between CCP2, CCP3, and CCP3.1) and anti-Sa in 10%. After 3?years, no change in the RF prevalence and anti-CCP was observed, but the anti-Sa increased to 17.5% (P?=?0.001). The percentage of patients in remission, low, moderate, and intense disease activity, according to the DAS 28, was of 0, 0, 7.5, and 92.5% (initial evaluation) and 22.5, 7.5, 32.5, and 37.5% (after 3?years). There were no associations of the presence of autoantibodies in baseline evaluation and in serial analysis with the percentage of clinical remission during follow-up of 3?years The presence of autoantibodies in early RA has no predictive value for clinical remission in early RA.     

Predictive value of antibodies to cyclic citrullinated peptide in patients with very early inflammatory arthritis

OBJECTIVE: To study the prognostic value of antibodies to cyclic citrullinated peptide (anti-CCP) and rheumatoid factor (RF), alone and in combination, in patients with very early synovitis. METHODS: A cross-sectional study was performed in patients with established inflammatory and noninflammatory disease to validate the assay in our unit and confirm previously reported sensitivities and specificities of anti-CCP antibodies. Subsequently, patients with synovitis of 3 months' duration were followed for 72 weeks and the ability of anti-CCP antibodies and RF to predict the development of rheumatoid arthritis (RA) and persistent inflammatory arthritis was assessed. RESULTS: One hundred twenty-four patients were assessed in the initial cross-sectional study. Anti-CCP antibodies and RF were detected by ELISA in only 4% of patients with non-RA inflammatory disease and in no patient with noninflammatory disease. Ninety-six patients with very early synovitis were assessed longitudinally. In these patients with early arthritis, the combination of anti-CCP antibodies and RF had a specificity, positive predictive value (PPV), sensitivity, and negative predictive value (NPV) for a diagnosis of RA of 100%, 100%, 58%, and 88%, respectively. The specificity, PPV, sensitivity, and NPV of this antibody combination for the development of persistent disease-fulfilling classification criteria for RA were 97%, 86%, 63%, and 91%, respectively. CONCLUSION: In patients with synovitis of 3 months' duration, a combination of anti-CCP antibodies and RF has a high specificity and PPV for the development of persistent RA. This autoantibody combination can be used to identify patients with disease destined to develop RA who may be appropriate for very early intervention.     

Carbamylated vimentin represents a relevant autoantigen in Latin American (Cuban) rheumatoid arthritis patients

Smoking produces substances that activate proinflammatory, prothrombotic and vasoconstrictive mediators via posttranslational carbamylation of proteins. As a new consequence of carbamylation, induction of anti-carbamylated autoantibodies were observed in rheumatoid arthritis (RA) patients, sometimes prior to onset of the disease. The overall aim of this study was to characterize the reactivity of different isotypes of autoantibodies against carbamylated antigens of vimentin in relation to established rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPA) and markers of disease activity in a so far largely uncharacterized population of Latin American (Cuban) patients with RA. Antigenic properties of carbamylated vimentin as well as vimentin peptides were analyzed in 101 patients with RA, 50 disease controls and 51 healthy controls. The diagnostic performance was compared with established commercial ELISA rheumatoid factor, anti-cyclic citrullinated peptide antibodies of second generation (anti-CCP2) and anti-mutated citrullinated vimentin (anti-MCV) antibodies. Prevalence of anti-MCV IgG (86 %), anti-carbamylated vimentin (carbVIM) IgG (77 %) and anti-carbamylated MCV (carbMCV) IgG antibodies (65 %) was higher than the classical RF IgM (60 %) and anti-CCP2 IgG (52 %) in this RA cohort. Of note, smoking status was associated with positive IgG antibody reactivity against CCP2 in 75.0 % and against MCV in 90 % of patients. Furthermore, IgM antibody response against carbMCV and carbVIM was observed in 80 and 90.0 % of smokers, respectively. Due to a high sensitivity of the IgM antibody isotype of anti-carbVIM of 85.2 %, the combination of ACPA with anti-carbVIM IgM provided the best diagnostic performance so far achieved in a RA cohort of this ethnic origin. We demonstrate a high prevalence of anti-carbVIM antibodies and correlation with smoking in Latin American (Cuban) RA patients. Anti-carbVIM IgM represents an useful marker in ACPA-negative patients and, in combination with ACPA IgG assays, optimizes the strategy for autoantibody testing.     

Is rheumatoid factor still a superior test for the diagnosis of rheumatoid arthritis?

The diagnosis of rheumatoid arthritis (RA) is based primarily on the 1987 revised American College of Rheumatology criteria for RA, which considers mainly the clinical symptoms. But typical clinical symptoms of RA are not manifested completely in early disease course. On the other hand, appreciable advantages have been made in the therapeutic strategy of RA in the last decade and highly effective disease-modifying anti-rheumatic drugs are available now for the control of RA. The treatment strategy for the control of early RA is aggressive. Thus, a highly specific and early diagnostic marker is needed for the detection of RA. Our study is an attempt to see the role of anti-CCP2 antibody (claimed to be highly specific and early diagnostic tool) in the diagnosis of RA. We studied 119 cases of RA in terms of clinical symptoms, disease duration and various autoantibody [including rheumatoid factor (RF), anti-CCP2 antibody, antinuclear antibody, anti-dsDNA] and C-reactive protein status. All the tests were also performed in 26 age and sex-matched healthy controls. Estimation of antibodies was done by quantitative ELISA. IgM RF was positive in 47.89% cases (p value = 0.000), followed by IgG RF (42.01%, p = 0.000) and IgA RF (36.97%, p = 0.000). RF was positive in 64.7% RA cases (p value = 0.000) when all three isotypes were tested together. RF was also detected in one healthy control. In 92 cases, anti-CCP2 Ab was done, hence other data were analyzed further in 92 cases only. Anti-CCP2 Ab was positive (cut-off = 15.0 U/ml) in only 50% RA patients but none of the healthy controls was positive for it. Swelling of joints was seen in 82.6% anti-CCP2 Ab positive cases (p value = 0.092) when compared with anti-CCP2 Ab negative cases (67.4%) while among RF positive cases, only 65.4% ((p value = 0.010) cases had swelling of joints. Out of 39 RA cases presenting with disease duration less than 1 year, only 48.71% patients were anti-CCP2 Ab positive while RF was positive in 61.53% patients. Utility of various combined autoantibody tests revealed that if one does all isotypes of RF (IgG, IgA and IgM) only, then 64.7% RA cases can be diagnosed and if anti-CCP2 Ab is added to it, the sensitivity increases to 75.56%. Thus, our study concludes that anti-CCP2 Ab is not a sensitive test for the diagnosis of RA neither it is useful in early diagnosis of RA, but it increases the sensitivity if added with all RF isotypes.     

Anti-microtubule organizing center with microtubule by autoimmune target test is also useful serological marker in rheumatoid arthritis evaluation

Seropositivity of rheumatoid factor (RF) or anti-cyclic citrullinated peptide antibody (anti-CCP) is one domain of scoring system in new American College of Rheumatology/European League against Rheumatism classification criteria for rheumatoid arthritis (RA). We investigated usefulness of antiperinuclear factor (APF) and autoantibody to microtubule organizing center with microtubule (anti-MTOC-MT), which was detected by autoimmune target (AIT) test, as serological markers for the diagnosis of early RA. The test results of 3,503 patients from the outpatient clinic of The Hospital for Rheumatic Diseases who underwent test for RF, APF, anti-CCP and anti-MTOC-MT simultaneously for the work-up of RA were analyzed. Four kinds of tests showed same results only in 53.1% (1,861/3,503) of all subjects. The kappa coefficient between each test was distributed from ?0.011 to 0.622. The agreement was best between RF and anti-CCP (kappa coefficient: 0.622), but the agreement was poor between anti-MTOC-MT and other 3 tests (kappa coefficient: 0.007 to ?0.025). In both of RF- and anti-CCP-negative patients, the patients who showed positive result for APF were 4.6% (160/3,503) and for anti-MTOC-MT were 13.2% (464/3,503). RF and anti-CCP positivity could not include all of APF and anti-MTOC-MT positivity. Anti-MTOC-MT detected by AIT test was independent serological marker, and it might be also helpful for the diagnosis of early RA. Therefore, the combined detection of all four serologic markers can be useful for the evaluation of suspected RA patients.     

Anti-agalactosyl IgG antibodies in sera from patients with systemic sclerosis

OBJECTIVE: To determine the prevalence and clinical correlations of anti-agalactosyl IgG antibodies (anti-AG IgG) in patients with systemic sclerosis (SSc). METHODS: Serum samples from patients with limited cutaneous SSc (lSSc; n = 49), diffuse cutaneous SSc (dSSc; n = 21), rheumatoid arthritis (RA; n = 10), systemic lupus erythematosus (SLE; n = 20), and healthy individuals (n = 20) were examined by lectin-enzyme immunoassay using human agalactosyl IgG as antigen. RESULTS: Anti-AG IgG were detected in 52 (74%) of 70 patients with SSc, which was much higher than the frequency of rheumatoid factor positivity in SSc (16%). Levels of anti-agalactosyl IgG antibodies were significantly higher than in healthy controls or patients with SLE, but lower than patients with RA. Levels of anti-AG IgG in patients with dSSc were significantly higher than in lSSc. SSc patients with anti-topoisomerase I antibodies had significantly higher levels of anti-AG IgG than SSc patients with anticentromere antibodies. Concerning clinical correlation, patients with pulmonary fibrosis showed elevated levels of anti-AG IgG compared to those without pulmonary fibrosis. Patients with decreased %VC or %DLCO showed increased levels of anti-AG IgG. Elevated levels of anti-AG IgG were associated with the presence of contracture of phalanges or cutaneous calcinosis, but not the presence of arthritis/arthralgia. CONCLUSION: The results suggest that anti-agalactosyl IgG antibody is frequently detected in SSc and is a serological indicator for more severe SSc.     

A comparison of performance of anti-cyclic citrullinated peptide 2 and citrullinated protein antibodies in the diagnosis of rheumatoid arthritis in Iranian patients

Antibodies to citrullinated proteins and rheumatoid factor (RF) are widely used in patients with rheumatoid arthritis (RA) and the antibodies to citrullinated proteins appear to be the most specific markers of the disease. The objective was to compare the diagnostic performance of the anti-cyclic citrullinated peptide 2 (anti-CCP2) and citrullinated protein Antibodies (CPA) with RF in the diagnosis of RA. Serum samples of 139 patients with RA and 131 patients with other rheumatic diseases were checked for anti-CCP2, CPA uses citrullinated recombinant rat filaggrin as the antigen assay, and RF. The specificity, sensitivity, and receiver operating characteristic (ROC) of tests were then compared. The sensitivity of anti-CCP2, CPA, and RF were 82.7, 83.5, and 61.5%, respectively. The specificities of the tests were 91.2, 78.6, and 90.5%, respectively. The area under ROC curves for the tests were 0.925, 0.890, and 0.847, respectively. Exclusion of overlaps was associated with improved specificity for CPA but no change in the specificity of RF and anti-CCP. The sensitivity of anti-CCP2, CPA, and RF were 66.7, 77.8, and 51.9% for patients with early RA, respectively. The findings of the present study indicate that anti-CCP2 might be of a better diagnostic value for the diagnosis of RA. They also showed that CPA and in the second place anti-CCP2 were useful in the diagnosis of early RA.     

Clinical evaluation of anti-mutated citrullinated vimentin by ELISA in rheumatoid arthritis

OBJECTIVE: Anti-cyclic citrullinated peptide (CCP) antibodies have emerged as sensitive and specific serological markers of rheumatoid arthritis (RA). However, antibodies to several other citrulline-containing proteins, including citrullinated fibrin and vimentin, have been detected in patients with RA, suggesting that citrulline is an essential constituent of autoantigens for RA-specific autoantibodies. We examined the diagnostic performance of the newly developed anti-mutated citrullinated vimentin (MCV) antibody assay. METHODS: Concentrations of anti-MCV, anti-CCP2, and rheumatoid factors (RF) were determined in the sera of 237 individuals: 119 patients with RA and 118 controls, including patients with other rheumatic diseases and healthy subjects. Diagnostic properties were compared by receiver-operating characteristic curve analysis. RESULTS: Using manufacturer's recommended cutoff values, sensitivity and specificity of anti-MCV antibodies were 75.6% and 91.5% in RA, compared to 66.4% and 98.3% for anti-CCP2. Introducing cutoff values to obtain the same 95% specificity resulted in decreased sensitivity of the anti-MCV test (69.7%) and increased sensitivity of the anti-CCP2 test (74.8%). At optimal cutoff levels, 29.4% of IgM RF-negative cases as well as 13.3% of anti-CCP2-negative cases in the RA group were anti-MCV-positive. Double-positivity for anti-MCV and anti-CCP2 provided 98.3% specificity with 97.5% positive predictive value in RA. CONCLUSION: Overall, the performance of the novel anti-MCV ELISA for the diagnosis of RA is similar to that of the anti-CCP2 test [area under the curve 0.853 (95% CI 0.801-0.905) vs 0.910 (95% CI 0.873-0.946); p not significant]. As the diagnostic spectrum of the anti-MCV assay is somewhat different from that of anti-CCP2, the combined application of the 2 assays can improve the laboratory diagnostics of RA.     

四种抗体联合检测在类风湿关节炎早期诊断中的应用价值

目的 探讨抗核周因子抗体(APF)、抗角蛋白抗体(AKA)、类风湿因子(RF)、抗环瓜氨酸肽抗体(抗-CCP抗体)联合检测在类风湿关节炎(RA)早期诊断中的临床应用价值。方法 对RA患者127例、非RA其他风湿病患者102例及正常对照组43例，采用速率散射免疫比浊法检测RF；酶联免疫吸附法定量检测抗-CCP抗体；免疫荧光法检测AKA、APF，并采用四格表法计算敏感度及特异性。结果RA组的RF、APF、AKA、抗-CCP抗体敏感度分别为65．4％、48．8％、32．3％、83．5％，特异性分别为73．5％、92．2％、93．1％、94．1％，同时出现三种抗体和四种抗体的特异性为99．0％、100％；非RA组无四种抗体同时出现的情况。结论 RF敏感性较高，但特异性较差；APF、AKA、抗-CCP抗体三种自身抗体对RA具有高度特异性，且在RA早期即可出现。四种抗体联合检测有助于提高RA的早期诊断率。