Diagnostic tests for rheumatoid arthritis: comparison of anti-cyclic citrullinated peptide antibodies,anti-keratin antibodies and IgM rheumatoid factors

OBJECTIVES: To examine the value of anti-cyclic citrullinated peptide (anti-CCP) antibodies, anti-keratin antibodies (AKA) and immunoglobulin M rheumatoid factors (IgM RF) in discriminating between rheumatoid arthritis (RA) and other rheumatic diseases, and to determine whether the clinical manifestations or severity of erosions in RA are associated with anti-CCP positivity. METHODS: In a cross-sectional study, we determined the concentrations or titres of these three markers in 179 RA patients and 50 controls. Erosions were quantified using the Larsen score in 129 patients. RESULTS: Sensitivity was highest for IgM RF (75%), followed by anti-CCP antibodies (68%) and AKA (46%). Specificity was highest for anti-CCP antibodies (96%), followed by AKA (94%) and IgM RF (74%). A correlation with clinical manifestations and severity of erosions was observed mainly for IgM RF positivity. CONCLUSIONS: With their excellent specificity, anti-CCP antibodies can be useful in establishing the diagnosis of RA, but IgM RF is a better predictor of disease severity.     

Autoantibodies in rheumatoid arthritis: association with severity of disease in established RA

Introduction: Autoantibodies in rheumatoid arthritis (RA) are useful both for diagnosis and prognosis. Antibodies directed against citrullinated antigens have recently been shown to predict development of RA as well as poor outcome in early arthritis. Data on their role in established RA is limited. We studied the association of various autoantibodies in RA with its severity. Materials and methods: A total of one hundred and twenty nine-patients with established RA was enrolled and sera were collected and stored at −70°C. Data regarding erosions, deformities, and extra-articular features were collected. IgM rheumatoid factor (RF) was measured using nephelometry and value above 20 U was considered positive. IgA RF was measured by enzyme-linked immunosorbent assay (ELISA) and value above the mean±2 SD of normal healthy control was taken as positive. Anti-keratin antibody (AKA) was detected by indirect immunofluorescence assay using rat esophagus as substrate. Anti-cyclic citrullinated peptide (CCP) antibodies were measured by commercial ELISA and a value above 5 U was considered as positive. Results: The prevalence of various autoantibodies was: IgM RF 82.2%, anti-CCP antibodies 82.2%, AKA 51.9%, and anti IgA RF 45%. The concordance rate of anti-CCP antibodies with IgM RF was 83%, with AKA 68%, and with IgA RF 60.5%. All but one patient positive for AKA were positive for anti-CCP antibodies. The presence of IgM RF, AKA, and anti-CCP antibody was associated with joint erosions and deformities. None of the antibodies had any association with presence of extra-articular features. No association of IgA RF was seen with erosions, deformities, or extra-articular features. Among 23 seronegative RA patients, 11 were positive for anti-CCP antibodies and 6 were AKA positive. The presence of anti-CCP antibodies was associated with presence of deformities (p<0.05). Conclusion: Anti-CCP antibodies are present in majority of patients with established RA including seronegative patients. Both anti-CCP and AKA, in addition to conventional marker like IgM RF, are associated with severe erosive disease.     

An eight year prospective study of outcome prediction by antiperinuclear factor and antikeratin antibodies at onset of rheumatoid arthritis

OBJECTIVES: Antikeratin antibodies (AKA) and antiperinuclear factor (APF) are specific antibodies found very early in rheumatoid arthritis (RA). The objective of this eight year follow up study was to assess the value of early AKA and APF assays in predicting functional disability and cartilage damage. METHOD: In 2000, 64 patients tested for AKA and APF (antifilaggrin antibodies) between 1990 and 1993 during evaluation of early symmetric oligoarthritis or polyarthritis (suspected RA) were invited to participate in this non-concurrent cohort study. The Health Assessment Questionnaire (HAQ) score, disease activity score (DAS), and Larsen radiographic score were the primary evaluation criteria. RESULTS: Twenty nine patients were re-evaluated. Clinical and laboratory data obtained in 1993 were similar in this group and in the 35 other patients. Twenty five patients had received a diagnosis of RA. Nine (31%) were rheumatoid factor (RF) positive, nine (31%) were AKA positive, and six (21%) were APF positive during the first year of the disease. APF was correlated with the Larsen score (p=0.011) and DAS (p=0.035) evaluated after a mean disease duration of 8.55 years. All APF positive patients had erosive disease. AKA was correlated with the DAS (p=0.035). CONCLUSION: The presence of AKA or APF early in the course of RA was associated with the DAS or Larsen score eight years later. The number of patients was small, but the findings confirmed those of studies with shorter follow ups. Antifilaggrin antibodies should be included in the initial investigation of patients with RA and, when positive, should alert to a high risk of poor outcomes.     

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.     

Anticitrullinated protein/peptide antibody assays in early rheumatoid arthritis for predicting five year radiographic damage

OBJECTIVE: To study the value of antibodies to citrullinated proteins/peptides for predicting joint outcomes in patients with recent onset rheumatoid arthritis (RA). METHODS: 191 patients with RA onset within the past year were followed up prospectively for five years. Serum samples obtained from 145 patients at baseline before disease modifying antirheumatic drug treatment were examined using three anticitrullinated protein/peptide antibody assays: antiperinuclear factor (APF) by indirect immunofluorescence (IIF), antikeratin antibodies (AKA) by IIF, and anti-cyclic citrullinated peptide (CCP) antibodies by enzyme linked immunosorbent assay (ELISA). Radiographs of the hands and feet taken at baseline and after three and five years were evaluated using Sharp scores modified by van der Heijde. RESULTS: Anti-CCP ELISA was positive in 58.9% of patients. APF/anti-CCP agreement was 77%. The likelihood of a total Sharp score increase after five years was significantly greater among patients with anti-CCP antibodies (67%; odds ratio (OR) 2.5; 95% confidence interval (95% CI) 1.2 to 5.0) or APF (57%; OR 2.4; 95% CI 1.2 to 4.9) but not rheumatoid factor (RF; OR 0.7; 95% CI 0.3 to 1.5). Mean values for radiographic damage, erosion, and joint narrowing scores at the three times were significantly higher in patients with anti-CCP or APF than in those without. AKA did not significantly predict radiographic damage. In separate analyses of patients with and without RF, anti-CCP or APF was better than RF for predicting total joint damage and joint damage progression after five years. CONCLUSION: Antibodies to citrullinated proteins/peptides determined early in the course of RA by APF IIF or anti-CCP ELISA are good predictors of radiographic joint damage. Further studies of clinical, laboratory, and genetic parameters are needed to improve RA outcome prediction in clinical practice.     

Second generation anti-cyclic citrullinated peptide (anti-CCP2) antibodies can replace other anti-filaggrin antibodies and improve rheumatoid arthritis diagnosis

We compared the diagnostic performance of anti-cyclic citrullinated peptide antibodies detected with second-generation enzyme immunoassay (anti-CCP2) with that of IgM-rheumatoid factor (RF), anti-perinuclear factor (APF), and anti-keratin antibodies (AKA). The sensitivity of anti-CCP2 was better than that of APF and AKA: they were detected in 25% rheumatoid arthritis (RA) patients without detectable APF or AKA. Their specificity, evaluated in other inflammatory rheumatic disease, was similar to that of APF and AKA. Despite the lower specificity, IgM-RF in combination with anti-CCP2 is interesting, as they do not completely overlap. Anti-CCP2 antibody detection seems to be a good alternative to other anti-filaggrin antibodies in the diagnosis 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。     

Antibodies against cyclic citrullinated peptide are associated with the DRB1 shared epitope and predict joint erosion in rheumatoid arthritis

OBJECTIVE: To evaluate antibodies against cyclic citrullinated peptide (anti-CCP antibodies) for their predictive value for severe joint destruction in rheumatoid arthritis (RA) and to examine their relationship to shared epitope (SE)-positive DRB1 alleles. METHODS: Concentrations of anti-CCP antibodies were determined in sera from 126 patients with recent onset RA who had been followed prospectively for 6 yr. Progression of joint destruction was evaluated according to Larsen by scoring radiographs from the hand and feet taken at baseline and after 1, 2, 4 and 6 yr of observation. In addition to clinical parameters, the presence of SE-positive DRB1 alleles and of rheumatoid factor IgM and IgA was determined. RESULTS: Anti-CCP antibodies were found more frequently and in higher concentrations in both DRB1*01-positive and in DRB1*04-positive SE-positive patients compared with SE-negative patients. Severe joint destruction as defined by a Larsen score in the upper third of the study population was predicted by positivity for anti-CCP antibodies, by the presence of SE-positive DRB1*04 alleles and by the presence of erosive disease at initial presentation. Multiple logistic regression analysis revealed that SE-positive DRB1*04 alleles and anti-CCP antibodies exerted a significant influence on the progression of joint destruction. CONCLUSION: The association of anti-CCP antibodies with DRB1*01 and with SE-positive DRB1*04 alleles implies a functional role for the SE sequence motif. The determination of SE-positive DRB1*04 alleles and of anti-CCP antibody positivity facilitates the prediction of disease course and prognosis at the time of initial presentation.     

Value of antibodies to citrulline-containing peptides for diagnosing early rheumatoid arthritis

OBJECTIVE: To compare the diagnostic values of antiperinuclear factor (APF), antikeratin antibody (AKA), and anti-cyclic citrullinated peptides (anti-CCP) to discriminate between patients with and without rheumatoid arthritis (RA) and to determine the diagnostic value of anti-CCP used alone or with other tests. METHODS: Two hundred and seventy patients with early arthritis underwent standardized investigations in 1995-1997. The clinical utility of APF, AKA, and anti-CCP in first-visit sera was evaluated using receiver-operating characteristic curves. Combinations of anti-CCP with other laboratory tests were assessed by multiple logistic regression. RESULTS: Anti-CCP, APF, and AKA were not perfectly correlated with one another. Anti-CCP with 53 UI as the cutoff was 47% sensitive and 93% specific, versus 52% and 79%, and 47% and 94%, for APF and AKA, respectively. Multiple logistic regression selected anti-CCP, AKA, IgM-rheumatoid factor (RF) ELISA, and the latex test. CONCLUSION: Rheumatologists can routinely use 2 or 3 tests for diagnosing RA (latex and/or IgM RF ELISA, and either AKA or anti-CCP ELISA) and can add a third or fourth test when the diagnosis remains in doubt.     

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.     

Prognostic laboratory markers of joint damage in rheumatoid arthritis

OBJECTIVE: To investigate whether determination of a set of laboratory markers at baseline provides prognostic information on joint damage in hands and feet in rheumatoid arthritis. METHODS: 183 patients with early rheumatoid arthritis included in a prospective study were examined. Radiographic changes in hands and feet at 5 and 10 years after inclusion were evaluated (Larsen). The markers analysed were: erythrocyte sedimentation rate (ESR); HLA-DRB alleles typed by restriction fragment length polymorphism; and C reactive protein, cartilage oligomeric matrix protein (COMP), rheumatoid factor (RF) (IgG, IgA, and IgM subtypes), antibodies against cyclic citrullinated peptide (anti-CCP), and antibodies against interleukin 1alpha (anti-IL1alpha), analysed by immunoassays. Multiple linear regression with backward elimination was used to determine the prognostic value of the variables. RESULTS: 117/176 patients were positive for IgG RF, 138/176 for IgA RF, 139/176 for IgM RF, 140/176 for anti-CCP, and 40/182 for anti-IL1alpha. After five years, ESR, the presence of IgA RF, serum COMP, and the presence of anti-CCP were significantly associated with more severe joint damage, and the presence of anti-IL1alpha with less severe joint damage. Baseline C reactive protein and anti-CCP predicted radiographic outcome after 10 years. A stronger prediction was obtained by combining the prognostic factors. CONCLUSIONS: Early determination of anti-CCP, IgA RF, anti-IL-1alpha, ESR, C reactive protein, and COMP predicted the development of joint damage in hands and feet in this cohort. A combination of these measures reflecting different aspects of the disease process should be useful for evaluating prognosis in individual patients with early rheumatoid arthritis.     

Isotypes of rheumatoid factors in rheumatoid arthritis and chronic liver diseases

We studied isotype-specific rheumatoid factors (RFs) to clarify their significance in rheumatoid arthritis (RA) and to verify the difference in RF isotypes between RA and chronic liver diseases (CLD). Isotype-specific RFs in RA and in CLD were measured by enzyme-linked immunosorbent assay (ELISA). Most sera (n = 51, 94.1%) from RA patients contained some kind of RF isotypes (92.1% for IgM RF, 76.4% for IgG RF, and 43.1% for IgA RF), and seronegative RA by ELISA was seen in only 11.8% (n = 6). The most characteristic combination of RF isotypes in active RA was IgG, IgA, and IgM. This combination of RF isotypes changed to IgG plus IgM, according to the diminution of RA activity; then, we found only IgM RF in inactive RA. The titers of each RF isotype also decreased in parallel with the activity of RA. IgA RF seemed to be the most sensitive factor for evaluating the activity of RA. In CLD, almost the same high frequency (n = 49, 89.8% for IgM RF, 59.2% for IgG RF), with the same titer levels seen in RA, was observed. On the other hand, IgA RF was significantly lower in frequency (n = 9, 18.4%) and in titer, compared with the finding in RA. Surprisingly, even in CLD, true seronegativity by ELISA was also found in very few patients (n = 4, 8.1%). In CLD, positive RFs detected by agglutination assay were seen more often in chronic hepatitis than in liver cirrhosis. In RA patients, significant associations of IgA RF and the serum concentration of IgA, and IgG RF and the serum concentration of IgG, were observed. On the other hand, in CLD patients, significant associations of IgG RF and the serum IgG concentration, and of IgM RF and the serum IgM concentration, were observed. These results indicated that IgA RF in active RA is the most characteristic RF isotype distinguishing it from other nonrheumatic diseases, as well as from inactive RA. RF isotypes reflected the background polyclonal B-cell activation in different manners in both diseases. In CLD, RF isotypes seemed to be disease-related immunological disorders reflecting disease progression. Received: February 17, 2000 / Accepted: July 5, 2001     

Ethnic differences in the prognostic utility of rheumatoid factor isotypes and anticyclic citrullinated peptides in rheumatoid arthritis patients: a cross-sectional study

Abstract

Objectives The prognostic significance of rheumatoid factor (RF) and anticyclic citrullinated peptide antibody (anti-CCP) in rheumatoid arthritis (RA) remains contentious due to the conflicting lines of evidence. This study aims to determine the association between RF isotypes and anti-CCP with disease severity in RA patients from three ethnic groups.

Methods A total of 147 RA patients from three different ethnic groups (Malays, Chinese, and Indians) who fulfilled the 1987 American College of Rheumatology (ACR) revised criteria for RA were recruited into this study. The seroprevalence of RF isotypes immunoglobulin (Ig)A, IgG, and IgM, as well as anti-CCP was determined using commercial enzyme-linked immunosorbent assay (ELISA) kits. Multinomial regression analysis was performed to assess the independent effects of autoantibody status on the development of deforming and erosive RA and the presence of extra-articular manifestations (EAM).

Results In Chinese patients, we found a significant association (p < 0.05) between IgG RF and anti-CCP and the presence of erosive disease, as well as IgM RF and IgG RF with the presence of joint deformities. In Indian patients, IgM RF was associated with deforming disease, whereas none of the antibodies were associated with disease severity in Malay patients. Multinomial regression analysis revealed that IgG RF was the most important predictor variable for erosive disease in Chinese patients, and IgM RF the only predictor variable associated with deforming disease in both Chinese and Indian RA patients.

Conclusions There is variability in the phenotypic association of RF isotypes and anti-CCP in relation to disease severity of RA in the three ethnic groups. RF, in particular, IgG and IgM, may be better prognosticators of severe disease in Chinese and Indian patients.     

Diagnostic value of anti-cyclic citrullinated Peptide antibody in patients with rheumatoid arthritis

OBJECTIVE: To explore the diagnostic value of anti-cyclic citrullinated peptide antibody (anti-CCP) detected by ELISA in patients with rheumatoid arthritis (RA). METHODS: The synthesized cyclic citrullinated peptide was used as substrate for ELISA. Anti-CCP antibody was detected by ELISA in 191 patients with RA, 132 with rheumatic diseases other than RA, and 98 with nonrheumatic diseases. The antiperinuclear factor (APF), anti-keratin antibody (AKA), rheumatoid factor (RF), and HLA-DR4 gene complex were also tested in each RA patient. The results of these tests were compared with anti-CCP antibody to examine the correlation between them. RESULTS: Ninety (47.1%) patients with RA, 4 (3.0%) with other rheumatic diseases, and 2 (2.0%) with nonrheumatic diseases were found to be anti-CCP antibody positive by ELISA. The sensitivity of anti-CCP antibody was 47.1%, with a high specificity (97.4%) in RA. Anti-CCP antibody correlated with APF, AKA, RF, and HLA-DR4 gene complex. CONCLUSION: A new modified anti-CCP antibody test had a moderate sensitivity (47.1%) but a high specificity (97.4%) in patients with RA and was found as a valuable supplement to diagnosis of RA. Anti-CCP correlated with APF, AKA, RF, and HLA-DR4 gene complex, but did not completely overlap with them. Anti-CCP antibody could be regarded as a new diagnostic marker for RA.     

Anti-CCP antibodies in rheumatoid arthritis and psoriatic arthritis

Our aim is to assess the prevalence and associated clinical features of anti-CCP (cyclic citrullinated peptide) antibodies for RF (rheumatoid factor)-positive and RF-negative rheumatoid arthritis (RA) and psoriatic arthritis (PsA). In a prospective, cross-sectional, multi-centre study, we determined the titres of anti-CCP antibodies in 208 RA patients (129 RF-positive, 79 RF-negative), 56 PsA patients and 39 healthy controls (HC). Clinical parameters including disease activity (disease activity score 28-DAS28), physical disability (health assessment questionnaire-HAQ), functional capacity (functional class) and radiological erosions were investigated in patients with RA. In PsA patients, clinical and radiological features were determined. Anti-CCP2 antibodies were measured using a second-generation anti-CCP enzyme-linked immunosorbent assay (Euro-Diagnostica, Netherlands). One-hundred four of 129 RF-positive RA (81%), 16 of 79 RF-negative RA (20%), seven of 56 PsA patients (12.5%) and none of the HC had anti-CCP antibodies. RA patients with anti-CCP antibodies had significantly higher disease activity, greater loss of function and more frequent erosive disease than anti-CCP antibody-negative group. In subgroup analysis, anti-CCP antibodies in RF-negative patients were also associated with erosive disease. All PsA patients with anti-CCP antibodies had symmetric arthritis with higher number of swollen joints. The prevalence of anti-CCP antibodies in RF-positive RA patients was significantly higher than in RF-negative RA and PsA patients. Anti-CCP antibodies were also associated with erosive disease in RF-negative RA patients. Both anti-CCP and RF tests were negative in 30% of the patients. Anti-CCP positivity was a frequent finding in PsA and associated with symmetrical polyarthritis.     

Measurement of biomarkers in juvenile idiopathic arthritis patients and their significant association with disease severity: a comparative study

OBJECTIVE: To evaluate in juvenile idiopathic arthritis (JIA) patients a biomarker panel of anti-cyclic citrullinated peptide (anti-CCP) antibodies, cartilage oligomeric matrix protein (COMP), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), IgM rheumatoid factor (RF), IgG RF, and IgA RF and compare to the presence of joint erosions (JE), joint space narrowing (JSN), and synovitis in order to evaluate aggressive disease. METHODS: Sixty-eight JIA patients (19 RF positive polyarthritis, 23 RF negative polyarthritis, 17 persistent oligoarthritis, and 9 systemic-onset) were evaluated using the biomarker panel and compared to 18 healthy controls. All RF isotypes, anti-CCP antibodies, and COMP were measured by enzyme-linked immunosorbent assays (ELISA). Statistically significant differences and associations were assessed for each biomarker in relation to JE, JSN, and synovitis. Multiple regression analysis was used to find the variables associated with joint damage and synovitis. RESULTS: Patients with JE and JSN had significantly elevated levels of IgA RF, IgM RF, and anti-CCP antibodies. COMP levels were higher in early disease, but also later in disease in patients with no JE or JSN. ESR, CRP, and IgA RF were significantly elevated in patients with active synovitis. Regression analysis showed IgM RF and disease duration to be associated with JE and JSN. Anti-CCP antibodies and COMP were also associated with JSN. CRP and IgA RF were associated with synovitis. CONCLUSION: Our findings demonstrate the importance of measuring IgM RF and IgA RF by ELISA and anti-CCP antibodies by ELISA, in addition to COMP in the assessment of JIA patients to determine severity of disease.     

抗瓜氨酸化蛋白抗体联合检测在类风湿关节炎中诊断价值的分析

目的 分别检测抗核周因子(APF)、抗角蛋白抗体(AKA)、抗环瓜氨酸肽(CCP)抗体,比较3种抗体在类风湿关节炎(RA)诊断中的敏感性和特异性,并探讨3种抗体联合检测在RA中的诊断价值.方法 选取2006-2008年在北京大学人民医院风湿免疫科就诊、具有关节症状的各种风湿病患者551例,其中,RA患者304例,其他风湿病患者247例.所有患者均检测APF、AKA和抗CCP抗体,其中J前两者采用间接免疫荧光法(IIF)检测,后者采用酶联免疫吸附试验(ELISA)法检测.结果 抗CCP抗体、AKA和APF对RA诊断的敏感性分别为76.2%、43.6%和34.5%,特异性分别为96.0%、98.4%和99.6%;3种抗体中任一抗体阳性对RA诊断的敏感性和特异性分别为77.3%和94.7%;3种抗体中任2项抗体阳性对RA诊断的敏感性和特异性分别为48.4%和99.2%,而3种抗体均阳性对RA诊断的特异性达100%,但敏感性仅28.3%.结论 3种抗瓜氨酸化蛋白抗体中,以抗CCP抗体对RA的诊断价值最高,联合检测抗CCP抗体、AKA和APF并不能显著提高对RA的诊断价值.     

Disease activity and joint damage progression in early rheumatoid arthritis: relation to IgG, IgA, and IgM rheumatoid factor.

The clinical and biochemical correlations with joint damage progression over two years in a consecutive group of 68 patients with rheumatoid arthritis with disease duration of less than two years are reported. Joint damage was assessed with Larsen's severity scale and a measure of change in progression rate constructed. Initial haemoglobin concentration, Ritchie index, and Waaler-Rose titre in combination accounted for one third of the variance in joint damage progression. Rheumatoid factor (RF) concentrations were followed with enzyme linked immunosorbent assays (ELISAs) for IgG RF, IgA RF, and IgM RF. The RF concentrations, except IgG RF, decreased with time; significant correlations between RFs and disease activity were few and barely clinically useful. After two years IgG RF correlated significantly with a radiological score if early non-erosive changes were omitted. All RFs tended to correlate better with this radiological score at all three observation points. Analyses of the change in progression rate indicated a time delay between development of radiographic changes and increase of IgG RF. These results suggest an indirect relation between RFs and joint damage. Clinical and biochemical improvements in early RA occur despite joint damage progression, and conventional markers have insufficient predictive value.     

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。     

Prospective study of early rheumatoid arthritis. I. Prognostic value of IgA rheumatoid factor.

Thirty-three patients with early arthritis, 28 of whom developed classical/definite rheumatoid arthritis (RA), were followed up for two to four years. Rheumatoid factor (RF) levels of the IgM, IgA, and IgG isotypes were measured in serum and synovial fluid by an ELISA technique developed in our laboratory. All seven patients who presented with raised IgA RF developed erosions of their hands and wrists. This was significantly different from the remaining 26. By contrast none of the five patients who presented with isolated elevation of IgM RF developed erosive disease. The patients with raised IgA RF needed significantly more treatment with 'specific' drugs than the remaining 26. It is suggested that the detection of IgA RF in early RA indicates poor prognosis, justifying a more aggressive treatment at an early stage.