Session Title: Rheumatoid Arthritis - Human Etiology and Pathogenesis
Session Type: Abstract Submissions (ACR)
Anti-carbamylated protein (anti-CarP) antibodies have been described in rheumatoid arthritis (RA) and arthralgia patients [1;2] and occur in subsets of the anti-CCP2 positive and negative patients [1;3]. In anti-CCP2 negative RA patients the presence of anti-CarP was associated with more severe joint destruction . Here we investigated the sensitivity and specificity of anti-CarP antibodies for RA in a setting of early arthritis.
Anti-carbamylated fetal calf serum (anti-Ca-FCS), anti-CCP2 antibodies and rheumatoid factor (RF) IgM were measured by ELISA using serum samples available from a large inception cohort; the Leiden Early Arthritis Clinic cohort (EAC). For the anti-CarP antibodies we used as a cut-off for positivity the mean + 2 times the standard deviation of the healthy controls .
In total 2086 sera of Leiden EAC patients suffering from early arthritis were analyzed for the presence of anti-Ca-FCS antibodies. Anti-CarP antibodies were present in 26% of the patients and in 2% of the controls. We observed that the sensitivity and specificity of anti-Ca-FCS in the EAC cohort for RA are 44% and 89%. As a reference the sensitivity and specificity of anti-CCP2 antibodies are 54% and 95% and for RF IgM are 59% and 90%. Analyzing the early arthritis patients that did not fulfil the EULAR/ACR 2010 criteria for RA that were anti-CarP positive (n=127) revealed that these patients were mainly diagnosed as undifferentiated arthritis (45%), reactive arthritis (9%), psoriatic arthritis (9%) or peripheral spondyloarthritis (8%).
Anti-CarP antibodies, as determined by the reactivity to carbamylated FCS, are predominantly present in RA but can also be detected in other forms of arthritis. The prognostic relevance of anti-CarP antibodies in these latter patients will have to be determined.
1. Shi J et al. Autoantibodies recognizing carbamylated proteins are present in sera of patients with rheumatoid arthritis and predict joint damage. Proc.Natl.Acad.Sci.U.S.A 2011; 108:17372-7.
2. Shi J, van de Stadt LA, et al. Anti Carbamylated Protein Antibodies (anti-CarP) are present in arthralgia patients and predict the development of rheumatoid arthritis. Arthritis Rheum. 2012.
3. Jiang X, Trouw LA, et al. Anti-CarP antibodies in two large cohorts of patients with rheumatoid arthritis and their relationship to genetic risk factors, cigarette smoking and other autoantibodies. Ann.Rheum.Dis. 2014.
H. W. van Steenbergen,
J. A. B. van Nies,
E. W. N. Levarht,
A. H. M. van der Helm- van Mil,
T. W. J. Huizinga,
R. E. M. Toes,
L. A. Trouw,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-specificity-of-anti-carbamylated-protein-antibodies-for-rheumatoid-arthritis-in-a-setting-of-early-arthritis/