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Anti-carbamylated protein (anti-CarP) antibodies precede the onset of rheumatoid arthritis
  1. Jing Shi1,
  2. Lotte A van de Stadt2,3,
  3. E W Nivine Levarht1,
  4. Tom W J Huizinga1,
  5. Dörte Hamann4,
  6. Dirkjan van Schaardenburg2,5,
  7. René E M Toes1,
  8. Leendert A Trouw1
  1. 1Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
  2. 2Division of Rheumatology, Jan van Breemen Research Institute | Reade, Amsterdam, The Netherlands
  3. 3Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
  4. 4Division Diagnostic Services, Sanquin Blood Supply, Amsterdam, The Netherlands
  5. 5Department of Rheumatology, VU University Medical Center, Amsterdam, The Netherlands
  1. Correspondence to Dr L A Trouw, Department of Rheumatology, Leiden University Medical Center, C1-R, LUMC, PO Box 9600, Leiden 2300 RC, The Netherlands; l.a.trouw{at}


Objective The presence of anti-citrullinated protein antibodies (ACPA) and IgM-rheumatoid factor (IgM-RF) years before the clinical diagnosis of rheumatoid arthritis (RA) suggests they are possibly involved in the pathogenic process underlying RA. In this study, we analysed whether anti-carbamylated protein (anti-CarP) antibodies, a novel autoantibody system against carbamylated proteins, can also be detected in healthy individuals before they developed RA.

Methods Multiple sera from asymptomatic blood donors prior to the onset of their RA symptoms and sera from age-matched and sex-matched controls were tested for the presence of antibodies directed against carbamylated-fetal calf serum (Ca-FCS), carbamylated-fibrinogen (Ca-Fib), cyclic citrullinated-peptide 2 and IgM-RF.

Results Anti-Ca-FCS and anti-Ca-Fib antibodies were each present in 27% and 38% of the last serum samples of blood donors prior to the diagnosis of RA. Both anti-Ca-FCS and anti-Ca-Fib antibodies could be detected many years before the onset of RA. Anti-CarP antibodies as well as ACPA are, on average, detected earlier than IgM-RF.

Conclusions In addition to ACPA and IgM-RF, also the newly identified anti-CarP antibodies appear many years before the diagnosis of RA.

  • Early Rheumatoid Arthritis
  • Autoantibodies
  • Ant-CCP
  • Rheumatoid Factor

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