anti-CCP Assay Research Articles

Anti-citrullinated α-enolase peptide as a highly sensitive autoantigen in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common autoimmune rheumatic disease in Taiwan. Anti-cyclic citrullinated peptide (anti-CCP) assay is widely used for RA diagnosis; however, not all anti-CCPs are detectable in RA-joint lesions. Citrullinated α-enolase peptide (CEP), which has a unique immunodominant epitope, can be detected in synovial fluid. Here, we aimed to evaluate the potential of anti-CEP as a serologic marker for the early diagnosis of RA and a prognostic predictor of joint destruction. We also determined the association of single-nucleotide polymorphisms (SNPs) in genes with the serological status and clinical characteristics of RA. Clinical records of 30 patients with RA were collected, and their serum and DNA samples were evaluated using enzyme-linked immunosorbent assay (ELISA) and SNP cross-reaction analysis. A considerable amount of anti-CEP was detected in patients with RA, a trend similar to that of anti-CCP. Moreover, anti-CEP was considerably associated with the protein-arginine deiminase type-2 SNP rs1005753.

The diagnostic and prognostic value of IgG and IgA anti-citrullinated protein antibodies in patients with early rheumatoid arthritis.

Anti-citrullinated peptide antibodies (ACPA) are specific markers for rheumatoid arthritis (RA) and typically measured by assays employing a cyclic citrullinated peptide (CCP) as antigen. This study was aimed at investigating the diagnostic performance of anti-CCP2 and anti-CCP3 IgG and IgA assays in patients with early RA with a particular focus on the potential prognostic value of IgA ACPA. The anti-CCP3.1 assay (Inova Diagnostics) measuring IgG and IgA antibodies simultaneously was compared to anti-CCP2 IgG and IgA assays (Thermo Fisher Scientific) employing sera of 184 early RA patients, 360 disease controls and 98 healthy subjects. Anti-CCP2 IgG and IgA assays showed high specificity versus disease controls (98.9%; 99.4%). Sensitivity was 52.2% (IgG) and 28.8% (IgA), resulting in positive likelihood ratios (LR+) of 47.5 (IgG) and 48.0 (IgA). The anti-CCP3.1 assay proved slightly more sensitive than the anti-CCP2 IgG assay (56%) but specificity was markedly lower (90.8% versus disease controls). However, when using a threefold higher cut-off specificity of the anti-CCP3.1 assay increased (97.5%) while sensitivity (52.7%) became comparable to the anti-CCP2 IgG assay resulting in a LR+ of 21.5. Anti-CCP2 IgA antibodies did not increase the diagnostic sensitivity of ACPA testing, but IgA positive patients showed diminished responses to treatment with anti-TNF biologicals compared to patients who had only IgG antibodies. Specificity of ACPA assays should be adjusted to reduce the risk of misclassification and a false positive diagnosis. Determination of ACPA IgA might provide important prognostic information concerning therapeutic responses.

Comparison of different assays for the detection of anticyclic citrullinated peptide antibodies in patients with rheumatoid arthritis.

ObjectiveTo evaluate a novel fully automated immunoturbidimetric assay developed by Qiangsheng Biotechnology Company for the detection of anticyclic citrullinated peptide antibodies (anti-CCP) in serum of patients with rheumatoid arthritis (RA) and compare it to the conventional EUROIMMUN- anti-CCP ELISA. Two other commonly used automated assays, the Elecsys anti-CCP assay, an ECLIA that is run on the Modular Analystics E170 (Cobas Diagnostics, Germany), and an anti-CCP CLIA developed by YHLO that is run on the iFlash 3000 Chemiluminescence Immunoassay Analyzer, were included as reference standards.MethodsA total of 264 serum samples were collected from patients attending the First People’s Hospital of Wenling affiliated to Wenzhou Medical University between July 2020 and November 2020. These included 131 serum samples collected from patients with RA, 70 serum samples collected from patients with other autoimmune diseases, and 63 serum samples collected from healthy controls at a physical examination. The clinical performance and sensitivity and specificity of the four anti-CCP assays for the diagnosis of RA were compared using receiver operating characteristic (ROC) curve analysis.ResultsThe Kappa statistic indicated almost perfect agreement between the EUROIMMUN-anti-CCP ELISA and the Elecsys anti-CCP ECLIA (Cobas) (0.863), the EUROIMMUN-anti-CCP ELISA and the anti-CCP CLIA (YHLO) (0.862), and the Elecsys anti-CCP ECLIA (Cobas) and the anti-CCP CLIA (YHLO) (0.816). On ROC curve analysis, AUC values were 0.955 for the EUROIMMUN-anti-CCP ELISA, 0.948 for the anti-CCP CLIA (YHLO), 0.947 for the Elecsys anti-CCP ECLIA (Cobas) and 0.903 for Qiangsheng, indicating all the assays had a good diagnostic performance for RA.ConclusionThe anti-CCP assays provided similar diagnostic information. The novel fully automated immunoturbidimetric assay for anti-CCP developed by Qiangsheng Biotechnology Company may be especially useful for large scale clinical screening in RA as it has a shorter testing time than the commercially available alternatives.

Prioritising referrals of individuals at-risk of RA: guidance based on results of a 10-year national primary care observational study

BackgroundMusculoskeletal (MSK) symptoms are among the commonest reasons for primary care assessments; however, few individuals will be diagnosed with an inflammatory arthritis (IA) within the following year. The purpose of this study was to investigate, in individuals with new MSK symptoms, the association between patient factors and risk of progression to IA, in order to optimise primary care referrals to rheumatology.MethodsIndividuals ≥16 years old with new non-specific MSK symptoms and no clinical synovitis were recruited by primary care across the UK from July 2007 until May 2019. Those testing positive for the anti-CCP2 assay (anti-CCP+) were invited to Leeds for follow-up. Subjects with a negative result (anti-CCP−) were sent a 1-year questionnaire, and general practitioners were contacted to confirm whether the individual had been diagnosed with an IA by a rheumatologist. Predictors for progression were assessed using multivariable regression analysis.ResultsSix thousand seven hundred eighty individuals were recruited: 3% were anti-CCP+, of whom 45% progressed to IA, predominantly rheumatoid arthritis. Anti-CCP+ participants with high antibody levels had an odds ratio (OR) for progression to IA of 9.42 [P < 0.001, 95% CI (3.13–28.30)], hand pain, OR 2.74 [P = 0.043, 95% CI (1.03–7.27)] and foot pain, OR 4.10 [P = 0.003, 95% CI (1.59–10.54)]. In low-level anti-CCP+ individuals, absence of pain in hands or feet had a negative predictive value of 96% for progression to IA.One-year follow-up data were available for 5640 anti-CCP− individuals, of whom 53 were diagnosed with IA (0.93%). Pain in hands, OR 2.51 [P = 0.018, 95% CI (1.17–5.39)] or knees, OR 3.03 [P = 0.003, 95% CI (1.47–6.25)] were associated with development of IA within 12 months.ConclusionsThis is the largest prospective primary care study of individuals at risk of IA, and the first one to prospectively investigate the outcome of MSK symptoms in a large anti-CCP− cohort. High anti-CCP levels and pain in hands/feet indicated an increased likelihood of progression to IA. In patients with low anti-CCP level and no pain in the hands/feet, progression is unlikely. In anti-CCP− patients, those with hand or knee pain were at increased risk of progression. This study demonstrates that routinely available tests and joint symptoms provide useful discrimination that may be used to prioritise referrals to rheumatology and avoid a delayed diagnosis.Trial registrationNCT, NCT02012764. Registered 25 January 2007.

The Specific Immunological Biomarkers Used In the Screening of Rheumatic Diseases from 2004 to 2020 at the Immunity Biology Center of the Pasteur Institut of Cote D’ivoire

Background: to study the epidemiological evolution of rheumatic diseases and to assess the advantages and disavantages of the methods for assaying rheumatic biomarkers. Patients and Methods: the study population consisted of 844 patients who came to the Pasteur Institute in Côte d’Ivoire from 2004 to June 2020 for the assay of rheumatic biomarkers. The parameters assayed were Rheumatoid Factor (RF) and Citrullinated Antipeptide Antibodies (Anti CCP). The RF assay was performed using two techniques: agglutination (RF latex, RF Waaler-Rose) and ELISA (CHORUS trio). The anti CCP assay was carried out by the ELISA technique (CHORUS trio). Results: among the 844 patients received, 144 had a positive result. Women made up the majority on the one hand of all patients (71%) and on the other hand of positive patients (77%). The most numerous patients were those aged between 41 and 60 years in both the total population and among the positive patients. The most common reasons for testing were rheumatoid arthritis and workup. The agglutination tests were used since 2004 for the determination of the RF from 2019 the RF was determined by ELISA chain. During this year 2019 there was a new more specific biomarker, the anti CCP assayed by ELISA. Conclusion: RF remains a key factor in rheumatic diseases. However, when combined with anti CCP, they make it possible to confirm the diagnosis with more specificity

Citrullinated Antigens with Multiple Citrulline Similar Motif in the Diagnosis of Rheumatoid Arthritis: A Preliminary Single-Center Study

The presence of anti-citrullinated protein antibodies (ACPAs) in the serum is one of the immunological features of rheumatoid arthritis (RA). Anti-cyclic citrullinated peptide (CCP) assay has been widely used in clinic for the diagnosis of RA. However, up to 40% of RA patients are anti-CCP negative and the diagnostic sensitivity in this population needs to be improved for better clinical management. In this study, peptides with Multiple Citrulline Similar Motif (MCSM) were synthesized and a new ELISA system, which we called RA_CP, was developed to detect citrullinated antigens with MCSM present in the serum. 106 RA,48 other arthritis patients and 41 sex- and age-matched healthy controls (HCs) were included in this study. Patients with RA have a significantly higher amount of citrullinated antigens with MCSM than other arthritis patients and HCs. RA patients with positive anti-CCP are also MCSM positive, whereas 75% anti-CCP negative patients are positive for MCSM. The diagnostic sensitivity for anti-CCP and MCSM was 81.1% and 95.3%, while the specificity was 100% and 94.4%, respectively. ROC curve analyses showed that the area under the curve (AUC) values were 0.906 (95% CI: 0.860-0.951) for anti-CCP and 0.948 (95% CI: 0.912-0.985) for MCSM while the combination of MCSM and anti-CCP test has the highest AUC (0.971, 95% CI: 0.946–0.996). Our results suggest that detection of citrullinated antigens with MCSM has improved sensitivity compared with anti-CCP assay and could serve as a biomarker in diagnosis of RA patients.

Comparison of the analytical and clinical performances of four anti-cyclic citrullinated peptide antibody assays for diagnosing rheumatoid arthritis.

Anti-cyclic citrullinated peptide antibody (anti-CCP) is one of the most important serologic markers for diagnosing rheumatoid arthritis (RA). This study aimed to compare the analytical and clinical performances of the second- and third-generation anti-CCP assays. Four automated anti-CCP assays were evaluated: Chorus anti-CCP (Diesse Diagnostica), Elecsys anti-CCP (Roche Diagnostics), Atellica® IM anti-CCP IgG (Siemens Healthineers), and Quanta Flash® CCP3 (Inova Diagnostics Inc.). Analytical performance included the precision, linearity, correlation, and concordance rate. For evaluating the clinical performance, 240 patient samples (120 positive and 120 negative samples, determined by the Chorus anti-CCP assay) were used, including those with a diagnosis of RA (n = 132) and non-RA (n = 108). Using receiver operating characteristic (ROC) curve analysis, the sensitivity and specificity were evaluated. All four assays that were evaluated showed good precision and linearity, and their correlation and concordance rates were in acceptable ranges. The area under the curve (AUC) values ranged from 0.888 to 0.914, showing a good diagnostic performance. The sensitivity and specificity of all assays were similar (88.0-97.2%). All four anti-CCP assays showed good analytical and diagnostic performances for diagnosing RA. After adjusting the cutoff values, these assays are expected to show enhanced sensitivity and specificity. Key Points • Previous studies have described the diagnostic performance of a few immunologic markers in RA diagnosis, but nothing has been proven to be sufficiently good in clinical practice. • All four automated anti-CCP assays showed good analytical and diagnostic performances for diagnosing RA in clinical practice. • After adjusting the cutoff values, these assays are expected to show enhanced sensitivity and specificity. • The present study provides reassuring evidence that any of the studied commercially available anti-CCP tests for detecting rheumatoid arthritis provide similar diagnostic information to institutions that adopt these specific testing systems.

THU0112 DIAGNOSTIC PERFORMANCE OF ANTI-CYCLIC CITRULLINATED PEPTIDE (CCP) 2 AND CCP3.1 ASSAYS IN EARLY RHEUMATOID ARTHRITIS

Background:Anti-cyclic citrullinated peptide (CCP) antibodies are the most specific markers for rheumatoid arthritis (RA). Different generations of assays have been developed among which the anti-CCP2 and anti-CCP3 assays are most widely used.Objectives:Since some differences between these assays have been reported it was our aim to compare their diagnostic performance and evaluate their usefulness for diagnostics of early RA.Methods:The anti-CCP3.1 assay (Quanta Lite®CCP3.1 IgG/IgA, Inova Diagnostics) was compared to anti-CCP2 IgG and IgA assays (EliATMCCP, Thermo Fisher Scientific) employing sera of 184 early RA patients, 360 disease controls and 98 healthy subjects.Results:Anti-CCP2 IgG and IgA assays showed high specificity versus healthy subjects (98.9%; 98%) and disease controls (98.8%; 99.4%). Sensitivity was 52.2% for the IgG and 30.4% for the IgA assay, respectively, resulting in high positive likelihood ratios (LR+) of 47.5 (IgG) and 50.7 (IgA). However, IgA antibodies did not show an added diagnostic value since all positive patients were also IgG positive. The anti-CCP3.1 assay was slightly more sensitive than the anti-CCP2 IgG assay (55.4%) but specificity was markedly lower and amounted to 95.9% versus healthy subjects and 90.8% versus disease controls resulting in a LR+ of only 6.0. Out of 360 disease controls 33 (9.2%) were found to be positive for CCP3.1 but among these only four (1.1%) were positive for anti-CCP2 IgG (and 2 of these also for anti-CCP2 IgA). The most common diagnosis of CCP3.1 positive control patients was osteoarthritis (12 patients); six patients suffered from spondyloarthropathies, two patients had reactive arthritis, 10 patients were diagnosed with an autoimmune rheumatic disease (AI RMD) and two patients had osteoporosis. However, at a cut-off of 60 AU/ml only nine disease controls remained positive (3 OA, 1 SpA, 4 AI RMD, 1 ReA) and 3 of them were also positive in the anti-CCP2 assay (ReA, SpA, SLE). When applying 60 AU/ml (high positive) as cut-off value at the early RA cohort, sensitivity (52.7%) became comparable to the anti-CCP2 assay and both specificity (97.5%) and LR+ (21.08) increased substantially.Conclusion:When interpreting the results of anti-CCP assays disease specificity should be taken into account in order to reduce the risk of misclassification and a false positive diagnosis.Table 1.Specificity, sensitivity and positive likelihood ratio (LR+) of CCP2 (IgG, IgA) and CCP3.1 assays.CCP3.1CCP2 IgGCCP2 IgACut-off (U/ml)201010Patients positive (n)1029656Specificity % (healthy subjects)95.999.098.0Specificity % (disease controls)90.898.999.4Sensitivity %55.452.230.4LR+ (healthy)13.552.015.2LR+ (disease controls)6.047.550.7Disclosure of Interests:Daniela Sieghart Grant/research support from: Thermo Fisher Scientific, Speakers bureau: Thermo Fisher Scientific, Christian Konrad Employee of: Thermo Fisher Scientific, Sascha Swiniarski Employee of: Thermo Fisher Scientific, Helmuth Haslacher: None declared, Daniel Aletaha Grant/research support from: AbbVie, Novartis, Roche, Consultant of: AbbVie, Amgen, Celgene, Lilly, Medac, Merck, Novartis, Pfizer, Roche, Sandoz, Sanofi Genzyme, Speakers bureau: AbbVie, Celgene, Lilly, Merck, Novartis, Pfizer, Sanofi Genzyme, UCB, Günter Steiner Grant/research support from: Thermo Fisher Scientific, Speakers bureau: Thermo Fisher Scientific

Comparison of second- and third-generation immunoassays for detection of anti-cyclic citrullinated peptide antibodies

Anti-cyclic citrullinated peptide antibodies (anti-CCPs) are important diagnostic markers for rheumatoid arthritis (RA). We evaluated the analytical and clinical performance of the QUANTA Flash CCP3 (INOVA Diagnostics, USA), a fully automated third-generation anti-CCP assay, in comparison with three second-generation anti-CCP (CCP2) assays. A total of 300 sera (67 from RA patients, 64 from other rheumatic diseases, 43 from osteoarthritis [OA], and 126 from other conditions) were tested with QUANTA Flash CCP3, Kallestad Anti-CCP II (Bio-Rad, USA), Elecsys Anti-CCP (Roche Diagnostics GmbH, Germany), and ARCHITECT Anti-CCP (Abbott Diagnostics, USA). Within-run and total imprecision (% coefficient of variation) of the QUANTA Flash CCP3 were <6%, and its linearity was acceptable over the claimed range (4.0–2,749.7 chemiluminescent units). The frequency of anti-CCP was similar between QUANTA Flash CCP3 and the other CCP2 assays in the RA (67.2% vs. 62.7–70.1%), other rheumatic diseases (7.8% vs. 6.3%), and OA (2.3% vs. 0–2.3%) groups. The concordance rate between QUANTA Flash CCP3 and the other assays ranged from 96.3% to 97.7% (kappa from 0.87 to 0.92). For the diagnosis of RA, the sensitivity/specificity was 67.2%/95.7%, 62.7%/98.3%, 70.2%/96.6%, and 67.2%/97.9%, and the areas under the receiver operating characteristic curves were 0.851, 0.791, 0.853, and 0.867 for QUANTA Flash CCP3, Kallestad, Elecsys, and ARCHITECT assays, respectively. The performance of the QUANTA Flash CCP3 was satisfactory and comparable to that of the three CCP2 assays. This fully automated assay would be a practical and reasonable option in clinical laboratories.

Anti-streptavidin IgG antibody interference in anti-cyclic citrullinated peptide (CCP) IgG antibody assays is a rare but important cause of false-positive anti-CCP results.

The detection of anti-cyclic citrullinated peptide (anti-CCP) IgG antibodies in blood is mainly used for the diagnosis of rheumatoid arthritis. Falsely elevated anti-CCP IgG antibodies due to anti-streptavidin IgG antibodies were suspected in our laboratory. In this study, we evaluated, in a standardized approach, the prevalence of anti-streptavidin IgG antibodies in a primary care setting and the effect of anti-streptavidin IgG antibodies on anti-CCP IgG assays from three different important commercial manufacturers (Abbott, Roche Diagnostics, Thermo Fisher Scientific). Three different populations were consecutively and prospectively studied: serum samples from 1000 ambulatory patients, 286 serum samples from patients for which anti-CCP was requested and 89 serum samples from patients which had previously given a positive anti-CCP result on Architect® i2000. The frequency of confirmed anti-streptavidin IgG-positive samples detected in this study was 0.6% (8/1375). Anti-CCP IgG was determined on the eight samples with confirmed anti-streptavidin IgG antibodies: with the Cobas® method, seven positive anti-CCP results were observed and five positive anti-CCP results with the Architect® method. No positive anti-CCP IgG results were obtained with the EliA™ method. Rheumatoid factor was negative in these eight samples. Anti-streptavidin IgG antibodies rarely cause false-positive results in some anti-CCP assays. However, despite being an infrequent assay problem, it could possibly lead to diagnostic confusion or even an incorrect diagnosis of rheumatoid arthritis.

Anticitrullinated protein/peptide antibody multiplexing defines an extended group of ACPA-positive rheumatoid arthritis patients with distinct genetic and environmental determinants

IntroductionThe second generation anticycliccitrullinated peptide (anti-CCP2) assay detects the majority but not all anticitrullinated protein/peptide antibodies (ACPA). Anti-CCP2-positive rheumatoid arthritis (RA) is associated with HLA-DRB1* shared epitope (SE) alleles and...

Anti-citrullinated protein antibodies in the diagnosis of rheumatoid arthritis (RA): diagnostic performance of automated anti-CCP-2 and anti-CCP-3 antibodies assays

This study compares the diagnostic performance of a second generation anti-cyclic citrullinated peptide antibody (CCP2) with a third generation anti-CCP antibodies assay (CCP3), as well as the combination of both tests. Serum samples of 127 patients were analyzed. IgG anti-CCP 2 and IgM rheumatoid factor were determined by EliA™ technique on a Phadia 250 instrument (Thermo Fisher Scientific), anti-CCP3 by the Quanta Flash™ anti-CCP3 IgG kit, BIO-FLASH Rapid Response Chemiluminscence Analyzer (INOVA Diagnostics). Diagnostic performance was compared using ROC-curves, sensitivity, specificity, likelihood ratios, and predictive values. Logistic regressions were used to investigate whether using both tests (anti-CCP2 and anti-CCP3) gives a better prediction of rheumatoid arthritis. At the manufacturer’s cut-offs sensitivity and specificity were 79.4 and 61.0% for CCP3 and 80.9 and 69.5% for CCP2. No significant differences could be observed regarding the areas under the curve (AUC) of both ROC-curves. The optimal cut-off point for CCP2 was 10.5 U/ml (sensitivity of 75.0% and specificity of 80.0%) and 5.6 U/ml for CCP3 (sensitivity of 86.9% and specificity of 61.0%). Binary logistic regressions indicated that the likelihood of having rheumatoid arthritis (RA) is significantly higher when testing positive on both CCP2 and CCP3 compared to CCP2 or CCP3 alone. In our cohort, comparable performance was found between the two CCP assays. Positivity for both CCP2 and CCP3 resulted in the most specific identification of RA patients. In patients with joint complaints suspected of having RA and with a weakly positive CCP 2 (≥7 and ≤16 U/ml) CCP3 testing could be of additive value for diagnosing RA.

Quality control and interest of the determination of anti-CCP antibodies and rheumatoid factor in the diagnosis of rheumatoid arthritis

The rheumatoid arthritis (RA) is an auto-immune, rheumatic and chronic inflammatory disease, characterized by joints damage. The early diagnosis of RA allows the initiation of a treatment which offers to the patients more chance of remission and avoids the evolution towards the unrecoverable deformity of joints. The objective of this study is to evaluate the performance of recent tests for the determination of anti -CCP antibodies and FR by ELISA in Benin Republic. This analytical, retrospective (2 years 6 months) and prospective (7 months) study allowed us to collect 36 patients meeting the American College of Rheumatology (ACR) criteria for RA and 24 controls. A comparison was made with the latex agglutination test for rheumatoid factors and a search of rheumatoid factors (RF) on the one hand and anti-cyclic citrullinated peptide. In our study, the specificity of anti-CCP assay (100 %) is higher than that of RF-ELISA (91.7%). The sensitivity of RF-ELISA assay is higher (77.8 %) than that of anti-CCP assay (66.7%). The latex test for rheumatoid factors has a sensitivity of 33.3 %. The positive predictive value (PPV) of anti-CCP assay (100 %) is higher than that of RF-ELISA assay (93.33 %). The positive-likelihood ratio (LR+) of anti-CCP assay is higher than the LR+ of RF-ELISA assay (4.96). The negative-likelihood ratio (LR-) of anti-CCP assay (0.33) is higher than the LR- of RF-ELISA assay (0.24). In conclusion, the anti-CCP assay has the highest specificity and RF-ELISA assay shows the highest sensitivity. In conclusion, the association of the two assays enhances a better diagnosis value for RA.Asian J. Med. Biol. Res. September 2016, 2(3): 379-388

Anti-peptidyl-arginine deaminase 3 (PAD3) antibodies as a promising marker to measure joint damage in patients with rheumatoid arthritis.

Recently, antibodies directed against peptidyl arginine deiminase 3 and 4 (anti-PAD3/PAD4 antibodies), calcium-dependent enzymes that catalyze the conversion from arginine to citrulline, have been described. Furthermore, antibodies that cross-react between PAD3 and PAD4 cause increased PAD4 activity and consequently correlate with joint damage. This study analyzes the correlation of anti-PAD3 antibodies with joint damage. To validate the novel chemiluminescent immunoassay (CIA) for the detection of anti-PAD3 antibodies, 20 samples were tested by CIA and by immunoprecipitation (IP). Next, 39 RA patients with available joint erosion score (JES), Total Sharp Score (TSS) and Joint Space Narrowing Score (JSNS) were tested for anti-CCP (using different methods) and anti-PAD3 antibodies by CIA. Excellent correlation was observed between the CIA and IP for the detection of anti-PAD3 antibodies (rho=0.85, p<0.0001). The median JES of our 39 patients was 14.1 with a standard deviation of 11.5. Anti-PAD3 antibody levels (rho=0.39, 95% CI=0.1-0.6; p=0.0149) were correlated with JES. No correlation was found with TSS and JSNS. In this cohort, ACPA measured using different anti-CCP assays did not correlate with the JES. In our cohort, anti-PAD3 antibodies correlate with joint erosion score. Therefore, anti-PAD3 antibodies might represent promising markers to predict joint damage in RA patients.

A Study on the Importance of Anti Cyclic Cytrullinated Peptide Antibodies (Anti-CCP) and Rheumatoid Factor (RF) Assay in Detection of Patients with Rheumatoid Arthritis in North Eastern Part of India

<i>Objective:</i> Rheumatoid arthritis (RA) is a polyarticular and systemic chronic inflammatory autoimmune disease, occurring throughout the world. The aim of the present study is to observe the role of anti-CCP antibody and Rheumatoid Factor (RF) assay in diagnosing patients of rheumatoid arthritis in north-eastern part of India, in the state of Assam and also to evaluate the individual and combined sensitivity and specificity of anti-CCP antibody and RF assay in diagnosing RA. <i>Methods:</i> A total of 88 cases presenting with history of polyarthritis were included in the study of which the study group comprised of 57 clinically diagnosed cases of rheumatoid arthritis and control group comprised of 31 patients of non-RA rheumatic diseases having joint pain. Individual sensitivity and specificity of the above tests, and also the combined specificity of the two tests and also the three tests were calculated and the results of the tests were compared with each other to examine the correlation between them. <i>Results:</i> Sensitivity of anti-CCP ELISA, RF IgM ELISA and RF Latex test was 91.23%, 75.44% and 40.35% with specificity of 70.97%, 67.74% and 90.32% respectively. If the three tests are combined then the combined specificity of the three tests is 99.59%. One important observation was that out of 9 anti-CCP positive cases in the control group(n = 31) 5 cases were weakly positive (titer 6.25 – 20 U/ml), considering cut-off value 6.25 U/ml as mentioned by the kit.If these weakly positive cases in the control group are considered as negative, then specificity of anti-CCP ELISA increases from 70.97% to 87.1% which is more acceptable. <i>Conclusion:</i> From this study it is observed that anti-CCP antibodies are highly sensitive and specific for diagnosing RA. If this test is combined with RF IgM ELISA and Latex test then combined specificity can be increased more than 99%. However, weakly positive titers of anti-CCP antibodies are more prevalent in other non-RA rheumatic diseases in North-Eastern part of India.

Autoantibodies in prediction of the development of rheumatoid arthritis among healthy relatives of patients with the disease.

Although blood bank-based studies have shown that rheumatoid arthritis (RA)-related autoantibodies are present before the onset of RA, information on their positive predictive value (PPV) for development of RA in healthy individuals is scarce. This study was undertaken to assess the 5-year PPV of serum IgM rheumatoid factor (IgM-RF) and anti-cyclic citrullinated peptide (anti-CCP) for the development of RA among healthy relatives of patients with RA. Healthy relatives of RA patients were invited to participate in a cohort study. At baseline, information on participants' medical history was obtained, and serum levels of IgM-RF and anti-CCP antibodies were determined (by nephelometry and second-generation anti-CCP enzyme-linked immunosorbent assay, respectively). The subjects were followed up every 4 months via a structured interview (Community Oriented Program for Control of Rheumatic Diseases [COPCORD] questionnaire). When the COPCORD questionnaire indicated possible arthritis, subjects underwent an in-office rheumatology assessment including joint count. The study end point was defined as fulfillment of the American College of Rheumatology criteria for RA. Eight hundred nineteen initially healthy relatives of 252 patients with RA were included (69% female, 41% offspring, mean ± SD age 35 ± 12 years). Eleven (1.3%) were positive for both anti-CCP-2 and RF, 12 (1.5%) only for anti-CCP-2, and 16 (2%) only for RF. RA developed in 17 (2.1%) of the relatives during the 5-year followup (3,313 person-years for the seronegative group and 60.8 person-years for the anti-CCP-2-positive group). The PPV was 64% when both anti-CCP-2 and RF were positive and 58% when only anti-CCP-2 was positive. Offspring of patients with RA had an independent 3-fold increased risk of developing RA. Results of the present study indicate that the magnitude of risk for developing RA in healthy relatives of patients with RA can be estimated using simple routine laboratory tests.

Clinical validation of surface-enhanced Raman scattering-based immunoassays in the early diagnosis of rheumatoid arthritis.

We assessed the clinical feasibility of conducting immunoassays based on surface-enhanced Raman scattering (SERS) in the early diagnosis of rheumatoid arthritis (RA). An autoantibody against citrullinated peptide (anti-CCP) was used as a biomarker, magnetic beads conjugated with CCP were used as substrates, and the SERS nanotags were comprised of anti-human IgG-conjugated hollow gold nanospheres (HGNs). We were able to determine the anti-CCP serum levels successfully by observing the distinctive Raman intensities corresponding to the SERS nanotags. At high concentrations of anti-CCP (>25U/mL), the results obtained from the SERS assay confirmed those obtained via an ELISA-based assay. Nevertheless, quantitation via our SERS-based assay is significantly more accurate at low concentrations (<25U/mL). In this study, we compared the results of an anti-CCP assay of 74 clinical blood samples obtained from the SERS-based assay to that of a commercial ELISA kit. The results of the anti-CCP-positive group (n = 31, >25U/mL) revealed a good correlation between the ELISA and SERS-based assays. However, in the anti-CCP-negative group (n = 43, <25U/mL), the SERS-based assay was shown to be more reproducible. Accordingly, we suggest that SERS-based assays are novel and potentially useful tools in the early diagnosis of RA.

Clinical Significance of Combined Anti-Cyclic Citrullinated Peptide Antibody and Rheumatoid Factor Assays in Rheumatoid Arthritis Diagnosis

Objectives: This study aims to investigate the value of combined anti-cyclic citrullinated peptide (CCP) antibody and rheumatoid factor (RF) assays in the clinical diagnosis of patients with rheumatoid arthritis (RA). Patients and methods: Results of both anti-CCP and RF detection in 70 RA patients (13 males, 57 females; mean age 49.2±12.1 years; range 35 to 61 years) and 112 non-RA patients (35 males, 77 females; mean age 42.5±7.1 years; range 35 to 49 years) were retrospectively and statistically analyzed. Results: In RA patients, positive rates of anti-CCP and RF were 70.0% and 77.1%, respectively. These rates were significantly higher than the rates in non-RA patients (2.7% and 4.5%, respectively; p<0.05). The sensitivity of combined anti-CCP and RF assays was 87.1% compared to the sensitivities of a single item assay of 70% and 77.1% for anti-CCP and RF, respectively. However, the combined assay had slightly lower specificity. With respect to the diagnostic index and rate of total consistency, the combined assay was superior to any single item assay. Conclusion: Combined anti-CCP and RF assays are more valuable in diagnosing RA than any single item assay.

FRI0045 Performance of New Anti-Ccp Multiplexing Assay Comparing to ELISA Anti-Ccp3 Test

BackgroundACPA finds its place in early RA diagnosis. Improvements are made in measurement of ACPA with recently designed fluorescent-based microparticles immunoassay which allows the simultaneous detection of 4 anti-CCP autoantibody...

AB0039 The Frequency of Acpa-Specific B Cells in the Circulating Memory B Cell Pool of Patients with Rheumatoid Arthritis

BackgroundRheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by the presence of autoantibodies (AA) such as rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPAs). These AA do not...