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.     

Anti-cyclic citrullinated peptide-2 (CCP2) autoantibodies and extra-articular manifestations in Greek patients with rheumatoid arthritis

The objective of our study was to establish whether there is an association between rheumatoid arthritis with extra-articular manifestations (exRA) and anti-cyclic citrullinated peptide 2 (anti-CCP2) antibodies in Greeks. A retrospective study of 220 Greek patients with RA, 95 with exRA and 125 without extra-articular manifestations (cRA). Serum anti-CCP2 antibodies and IgM rheumatoid factor (RF) were measured. CCP2(+) were 65.3% of exRA and 58.4% of cRA patients. RF(+) were 69.5% of exRA and 60.0% of cRA patients. Among exRA patients, 37.9% had high serum anti-CCP2 antibody levels (>100 IU/ml) compared to 21.6% cRA patients (p = 0.008). Serositis and pulmonary fibrosis were found to be associated with high levels of anti-CCP2 antibodies (52.9 vs 26.6%, p = 0.02 and 63.6 vs 26.8%, p = 0.008, respectively). Serum RF levels were 265.0 ± 52.0 IU/ml (mean ± SEM) in exRA and 205.1 ± 40.6 (mean ± SEM) in cRA (NS). High serum RF levels (>268 IU/ml) were more likely to have sicca syndrome. In Greek patients with rheumatoid arthritis (RA), high serum anti-CCP2 antibodies are associated with serositis and pulmonary fibrosis. Therefore, anti-CCP2 antibodies have prognostic significance in patients with RA.     

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.     

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.     

Clinical utility of anti-carbamylated antibody in rheumatoid arthritis female patients: Emerging predictive value compared to anti-cyclic citrullinated peptide and rheumatoid factor

Aim of the workTo evaluate the frequency of anti-carbamylated protein (anti-CarP) antibodies positivity in female rheumatoid arthritis (RA) patients; to study their association with different disease aspects clinically and radiologically and to assess their potential predictive role of RA disease compared to other autoantibodies.Patients and methodsFifty-one RA female patients and 44 age-matched controls were studied. Duration of morning stiffness, disease activity score (DAS28) and health assessment questionnaire (HAQ) were assessed. Laboratory investigations included acute phase reactants, rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) and anti-CarP antibodies. Conventional radiography of both hands and feet was performed and assessed by a simple erosion narrowing score (SENS). All patients were evaluated by ultrasound 7 (US7) score.ResultsThe mean age of patients was 46.9 ± 8.6 years with disease duration of 6.2 ± 5.3 years. Anti-CarP antibody was positive in 52% and 54.5% of patients seronegative for anti-CCP and RF respectively. RF was positive in 40 (78.4), anti-CCP was positive in 26(51%), and anti-CarP in 21 (41.2%) patients. Anti-CarP antibodies were significantly associated with radiological damage, DAS28, HAQ and acute phase reactants. The sensitivity and specificity were 41.2% and 88.6%, respectively for anti-CarP, 51% and 93.2% for anti-CCP and 78.4% and 90.9% for RF to diagnose RA.ConclusionsAn association between anti-CarP antibody positivity and the disease activity, severity, structural damage and hence poor disease outcome has been demonstrated. Testing anti-CarP antibodies could be a useful marker for the assessment of disease activity as well as the expectation of prognosis in RA patients.     

Anti-MCV antibodies predict radiographic progression in Greek patients with very early (&lt;3 months duration) rheumatoid arthritis

This study aimed to assess the diagnostic and prognostic value of anti-mutated citrullinated vimentin (MCV) antibodies in very early rheumatoid arthritis (VERA) and in established rheumatoid arthritis (RA). Seventy-one patients with undifferentiated arthritis (UA) of <3 months duration, 141 with established RA, 53 with other rheumatic diseases, and 40 healthy individuals were included in the study. Anti-MCV, anti-cyclic citrullinated peptide (CCP) antibodies, and rheumatoid factor (RF) were determined and hand radiographs were recorded. Patients were assessed prospectively for 2 years, and hand radiographs were repeated. Diagnostic performance of anti-MCV was studied with receiver operating characteristic (ROC) curves and evaluation of sensitivity, specificity, and likelihood ratios. Forty-six percent of UA patients progressed to RA at 2 years. In VERA patients, sensitivity of anti-MCV was 52 %, compared to 44 % of anti-CCP and 37 % of RF, while specificity was 91 %, compared to 91 % of RF and 84 % of anti-CCP. Anti-MCV were detected in 25 % of VERA patients negative for both anti-CCP and RF. In established RA, anti-MCV did not sustain its diagnostic performance. By multivariable analysis, anti-MCV, but not anti-CCP or RF, showed significant correlation with radiographic progression in VERA patients. In established RA, anti-MCV, anti-CCP, and RF were associated with active disease (p ≤ 0.03) and joint damage (p ≤ 0.004). By multivariate analysis, the strongest factors for radiographic damage were disease duration (p = 0.000), HAQ score (p = 0.000), and RF (p = 0.002). In conclusion, in patients with very early UA, anti-MCV predict both progression to RA and radiological damage, and therefore, anti-MCV antibody testing may be useful in every day practice.     

Relation of rheumatoid factor and anti-cyclic citrullinated peptide antibody with disease activity in rheumatoid arthritis: cross-sectional study

To analyze the association of rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (anti-CCP) with non-remission and with disease activity measures in rheumatoid arthritis (RA). Cross-sectional study of consecutive RA patients. Non-remission was defined as a disease activity score (DAS28) ≥2.6 at study enrollment. The Simplified Disease Activity Index (SDAI) and the Clinical Disease Activity Index (CDAI) were additionally measured. Serum titers of RF and anti-CCP were transformed into incremental levels (100/units) and log-transformed levels. Analysis of association with non-remission was done with logistic regression models, with and without adjustment for age, sex, disease duration, and corticoid use. Multiple regression models, raw and similarly adjusted, were used to measure the association of RF and anti-CCP with the disease activity measures. A total of 385 patients were included, of whom 286 (74 %) were not in remission. Log-transformed RF level was associated with an increased risk of non-remission after adjustment (OR = 1.32, 95 % CI 1.04–1.67). This association was especially evident in patients with less than 10 years of disease duration (OR = 1.51, 95 % CI 1.15–1.99) and in those using steroids (OR = 2.06, 95 % CI 1.22–3.48). Serum RF titers and log-transformed RF levels showed a small but significant association with DAS28 score (adjusted beta coefficients 0.002 and 0.18, respectively; both p ≤ 0.01), but neither with SDAI or CDAI nor with anti-CCP antibody. : Log-transformed RF levels might be associated with non-remission in RA, especially in patients with short disease duration or on steroids.     

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.     

Diagnostic utility of anti-cyclic citrullinated peptide antibodies for very early rheumatoid arthritis

OBJECTIVE: To compare the diagnostic utility of anti-cyclic citrullinated peptide (anti-CCP) antibodies with other serological markers including rheumatoid factor (RF), anti-agalactosyl immunoglobulin G (IgG) antibody, and matrix metalloproteinase (MMP)-3 in very early rheumatoid arthritis (RA). METHODS: Serum concentrations of anti-CCP antibodies, RF, anti-agalactosyl IgG antibody, and MMP-3 were measured in 262 patients with RA ("total RA") including 55 patients with disease duration of less than 6 months who had not been treated before entry ("very early RA") and 116 patients with rheumatic diseases other than RA. RESULTS: The diagnostic sensitivity of anti-CCP antibodies was 82.4% in total RA and 67.3% in very early RA and was lower than that of RF (84.0% total RA, 83.6% very early RA) and anti-agalactosyl IgG antibody (90.5%, 90.9%), whereas specificity, positive predictive value, and diagnostic accuracy were the best among markers tested both in total RA and in very early RA. The presence of either anti-CCP antibodies or RF increased the sensitivity, but any combination of serological markers was not significantly better in diagnostic accuracy than anti-CCP antibodies alone. The rates of RF-positive subjects in anti-CCP antibody-negative patients both in total RA (43.5%) and in very early RA (61.1%) were higher than those of anti-CCP antibody-positive subjects in RF-negative patients (38.1% and 22.2%, for total RA and early RA, respectively). CONCLUSION: Measurement of anti-CCP antibodies, by itself, is useful for the diagnosis of RA; however, combined use of anti-CCP antibodies with RF may be more useful than either method alone for the diagnosis of very early RA.     

The frequency of antibodies against cyclic citrullinated peptides and rheumatoid factor in healthy population: a field study of rheumatoid arthritis from northern turkey

Rheumatoid arthritis (RA) is a chronic, systemic and an autoimmune disease characterized by inflammation of the synovial membrane that affects approximately 1 % of the total world population. Rheumatoid factor (RF) is a widely used auto antibody in diagnosis of the RA and found positive in 50–80 % of the patients but with a lower specificity. On the other hand, anti-cyclic citrullinated peptide (anti-CCP) is the latest serological marker with a specificity around 98 %. This field survey was conducted in different regions to investigate the frequency of RF and anti-CCP and also frequency of RA in a northern province of Turkey. This study was conducted in 70 local areas (12 urban and 58 rural) in the province of Tokat, which is located in northern Turkey. The population of Tokat was reported to be 828,000 at the last census and about 530,000 individuals aged > 18years old. The study population of 941 subjects (462 male and 479 female; urban 501 and rural 440) was selected by random sampling method among 530,000 individuals. Of the 941 healthy controls assigned to the study, 479 of them were female (51 %) and 462 of them were males (49 %), and median age of all participants was 41 ± 17. Twenty-six subjects were RF positive (2.8 %), and 9 patients were anti-CCP positive (1 %). The presence of both RF and anti-CCP antibodies has also been shown in two patients (0.2 %). In conclusion, we demonstrated that the frequency of RA was 0.53 %, RF presence was 2.8 %, and anti-CCP presence was 1 % in total 941 healthy subjects enrolled into study.     

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.     

Follow-up of primary Sjogren’s syndrome patients presenting positive anti-cyclic citrullinated peptides antibody

Anti-cyclic citrullinated peptide antibody (anti-CCP antibody) is very useful for the diagnosis of rheumatoid arthritis (RA) and is associated with articular erosions. The specificity of anti-CCP antibody in the diagnosis of RA has been reported to be about 95 %. Because of its higher specificity in RA, we assessed the clinical features of primary Sjogren’s syndrome (pSS) who were positive for anti-CCP antibody. We assessed the clinical features of 405 pSS patients. After 60 (range 7–98) months, 23 (5.6 %) patients previously diagnosed with pSS had progressed to RA. Comparing the anti-CCP positive group with the negative group, laboratory test results for anti-CCP titer and rheumatoid factor positivity with respect to clinical outcome and progression to RA, arthralgia and arthritis were significantly different. Multivariate regression analysis also showed that anti-CCP antibody titer was independently associated with progression to RA. The odds ratio of anti-CCP positivity in terms of progression to RA was 2.5 (95 % CI 1.7–3.7). Testing for anti-CCP antibody in pSS patients with arthritis may allow for the prediction of progression to RA.     

In palindromic rheumatism,hand joint involvement and positive anti-CCP antibodies predict RA development after 1 year of follow-up

This study aimed to determine the frequency of rheumatoid factor (RF) and cyclic citrullinated peptide (CCP) antibodies in a cohort of patients with palindromic rheumatism (PR) and to find determinants for progression to rheumatoid arthritis (RA). All new cases of PR (n?=?90) were included prospectively and followed up for 1 year, and a comparison group of RA cases (n?=?70) was also included. At study entry in all patients in both groups, RF and anti-CCP antibodies were tested, and the findings were compared and correlated. In the PR group at presentation, RF was positive in 30 patients (33.3 %) and, in the RA group, in 45 patients (64.3 %). Anti-CCP antibodies were positive in 35 patients (38.9 %) with PR and in 58 patients (82.9 %) with RA. In the PR group, positive correlations were observed between RF and C-reactive protein (CRP) (p?=?0.036), while anti-CCP positively correlated with disease duration (p?=?0.015) and CRP (p?<?0.001). At 1-year follow-up, 25 cases (27.5 %) had progressed to RA, 3 (3.3 %) cases had developed systemic lupus, 43 cases had responded to hydroxychloroquine with complete remission, five cases had developed other rheumatic diseases, and 14 cases had progressed to undifferentiated arthritis. After regression analysis, the involvement of hand joints and positive anti-CCP were the only predictors that determined progression into RA within a year (p?<?0.001 and p?=?0.02, respectively). Early hand joint involvement and positive anti-CCP at disease onset are good predictors for progression to RA in this domain.     

Diagnostic value and clinical significance of anti-carbamylated protein (anti-CarP) antibodies in Egyptian patients with rheumatoid arthritis

Aim of the workThe study was performed to assess the diagnostic potential of anti-carbamylated proteins (anti-CarP) antibodies in Egyptian patients with RA and their relation to clinical manifestations, laboratory findings and radiological damage.Patients and methodsThe study involved 90 RA patients and 90 matched healthy controls. Disease activity score (DAS28) and health assessment questionnaire (HAQ) were assessed. Plain x-ray hands and feet were performed and assessed by modified Larsen’s score. Laboratory investigations including acute phase reactants, rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) and anti-CarP antibodies were estimated.ResultsThe patients mean age was 42.6 ± 10.4 years (20–60 years), disease duration was 4.3 ± 3.3 years and were 82 females (91.1%) and 8 males (8.9%). The mean DAS28 was 4.9 ± 1.2, HAQ was 1.6 ± 0.7 and Larsen score 33.8 ± 12.2. 29/90 (32.2%) patients were positive for anti-CarP antibodies and were significantly associated with extra-articular manifestations and deformity (p < 0.001), but not with acute phase reactants. Anti-CarP antibodies significantly associated with modified Larsen’s (p < 0.001), but not DAS28 (p = 0.13). The sensitivity and specificity were 32.2% and 96.7% for anti-CarP antibodies, 61.1% and 97.8% for anti-CCP antibodies, 66.7% and 91.1% for RF respectively. 25.7% of anti-CCP negative patients showed anti-CarP positivity, and radiological damage was significantly associated with anti-CarP in them.ConclusionThe sensitivity of anti-CarP antibodies was low in comparison to both RF and anti-CCP; however, they showed high specificity and were detected in anti-CCP negative patients, so they could be useful to test beside anti-CCP and RF. Anti-CarP antibodies may reflect disease radiological damage.     

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.     

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。     

Usefulness of anti-CCP antibodies in patients with hepatitis C virus infection with or without arthritis,rheumatoid factor,or cryoglobulinemia

The presence of antibodies to cyclic citrullinated peptide (CCP) has high specificity in the diagnosis of rheumatoid arthritis (RA). Hepatitis C virus (HCV) infection may induce extra-hepatic manifestations, such as polyarthritis that mimic RA. The aim of this study was to determine the prevalence of anti-CCP antibodies in HCV-infected patients with or without arthritis, rheumatoid factor (RF), or cryoglobulinemia and to investigate whether anti-CCP antibodies may be helpful in discriminating patients with RA from patients with HCV-associated arthropathy. A total of 44 patients with RA, 34 patients with HCV infections, and 42 control patients with non-RA rheumatic diseases were recruited for the study. Anti-CCP antibody levels were determined by enzyme-linked immunosorbent assay. We found that, consistent with other reports, patients with RA were more likely to have high titers of anti-CCP antibody than HCV-infected or control patients. A significant number of HCV-infected patients with neither RF nor cryoglobulinemia were also positive for anti-CCP antibodies (the three positive values were 36.10, 8.65, and 5.83 U/ml, P < 0.01 compared with the control patients). The presence of cryoglobulinemia and/or RF in HCV-infected patients did not affect the anti-CCP outcomes. Although anti-CCP antibodies remain to be a very useful tool in discriminating RA from non-RA, HCV-infected patients with neither RF nor cryoglobulinemia may have anti-CCP antibodies. Because of limited patient numbers, this tentative conclusion may need further confirmation with inclusion of more patient population.     

Antibodies to citrullinated peptides in tuberculosis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by symmetric polyarthritis, rheumatoid factor (RF) positivity, and bone erosions. Recently, research has been conducted on anti-citrullinated peptide antibodies (ACPAs) to which there are greater sensitivity and specificity than RF. However, these antibodies have also been described in infectious diseases, particularly tuberculosis (TB), placing the high specificity of the test in doubt. The aim of this research was to study the prevalence of ACPAs in TB, RA, and healthy controls. Patients with bacteriologically confirmed pulmonary tuberculosis, RA (ACR criteria), in addition to healthy controls were included. ACPAs were researched by: anti-cyclic citrullinated peptide (CCP), anti-modified citrullinated vimentin (MCV), and RF by ELISA. The study was conducted in 50 TB patients, 50 with RA, and 20 controls. Anti-CCP antibodies were found in 39 (78 %) of the RA patients (median titer, 128 U), whereas anti-MCV antibodies were found in 25 (50 %). Of the patients with TB, two (4 %) had positivity for anti-CCP and anti-MCV and no patient in the control group tested positive for these antibodies. Sensitivity of anti-CCP for RA was 78 % (confidence interval (CI), 63 to 88 %) and specificity was 97 % (CI, 89 to 99 %) while the sensitivity of anti-MCV was 50 % (CI, 35–64 %) and specificity was 97 % (CI, 89 to 99 %). RF was positive in 40 samples (80 %) of RA, in 30 (60 %) of TB, and in 1 (5 %) of the controls. Our findings showed high sensitivity of anti-CCP and high specificity of both anti-CCP and anti-MCV antibodies for RA, even in a population with high incidence of tuberculosis. The higher frequency of positivity of ACPA in TB observed in previous studies may be attributed to methodological factors.     

Association of rheumatoid arthritis treatment response and disease duration with declines in serum levels of IgM rheumatoid factor and anti-cyclic citrullinated peptide antibody

OBJECTIVE: To examine the association of treatment response and disease duration with changes in rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody levels among patients with rheumatoid arthritis (RA). METHODS: The study sample included 66 RA patients who completed double-blind, randomized clinical protocols and for whom baseline and followup serum samples were available. Anti-CCP and RF levels were measured using commercially available assay kits. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to describe the association of response and disease duration with declines in antibody levels. RESULTS: Patients had a mean +/- SD age of 49.9 +/- 12.0 years and were predominantly female (n = 51; 77%). The mean +/- SD duration between the times at which the baseline and followup serum samples were obtained was 13.7 +/- 8.6 months. Among the 64 subjects with positive antibody at baseline, 33 (52%) experienced a > or =25% reduction in the anti-CCP antibody level during the course of treatment, and 35 patients (55%) had a > or =25% reduction in RF. After adjustment for the baseline anti-CCP antibody level, only a shorter disease duration (< or =12 months) was significantly associated with a decline in the level of anti-CCP antibody (OR 3.0, 95% CI 1.0-8.8), and no association with treatment response was observed. Conversely, treatment response was the only significant determinant of a decrease in RF levels (OR 3.6, 95% CI 1.2-10.4). CONCLUSION: Shorter disease duration predicts greater declines in anti-CCP antibody levels with treatment in RA. Although treatment response is a robust determinant of a decrease in RF, it does not appear to be associated with declines in the anti-CCP antibody level.