Rheumatoid Factor Screen ELISA Kit


Human rheumatoid factor screen ELISA kit is intended to screen in-vitro quantitative levels of IgM, IgA and IgG antibodies to anti-rheumatoid factor (RF, rheumatoid factor IgM/IgG/IgA, rheumatoid factor screen) in human serum and plasma. This assay has a minimum analytical sensitivity limit of 1.0 U/ml.


Rheumatoid factor (RF) can be found as a number of different isotypes for example IgA, IgD, IgE, IgG and IgM, however it is predominately as the IgM isotype. RF is an autoantibody which is identified as being against the Fc portion of IgG, it is produced by the immune system and can attack healthy tissues. Rheumatoid factors are very important diagnostic tool for the evaluating individuals that many be a suspect for arthritis (in particular rheumatoid arthritis). Rheumatoid factor is also present in many other diseases such as connective tissue diseases (Sjögren’s syndrome or systemic lupus erythematosus), infectious diseases (tuberculosis, syphilis and hepatitis), sarcoidosis and liver disease.


All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

  • Divisible Microplate: Consisting of 12 modules of 8 wells, Fc fragments of highly purified human Immunoglobulin G are coated on to microwells.
  • Calibrator A-E: Concentration 0-500 U/ml, made up from rheumatoid factor in a serum/buffer matrix.
  • Control Positive And Control Negative: Containing rheumatoid factor (RF).
  • Sample Buffer P (5x).
  • Enzyme Conjugate: Contains anti-human IgA, IgM and IgG antibodies, HRP labelled.
  • Substrate: 3,3’,5,5’- Tetramethylbenzidin (TMB).
  • Stop Solution: Contains acid.
  • Wash Buffer (50x).
  • Instruction For Use.
  • Certificate Of Analysis.


The minimum detection sensitivity level of human anti-rheumatoid factor IgM, IgG, IgA (RF-IgM/IgG/IgA, rheumatoid factor IgM/IgG/IgA) using current rheumatoid factor screen ELISA kit was 1.0 U/ml. The dynamic range for this assay is 15.0 – 500.0 U/ml.


– Rheumatoid Factor Screen (RF-IgM, RF-IgG, RF-IgA): ELISA
– Linearity: 90 – 105%
– Measuring Range: 0 – 500 U/ml
– Limit of detection (LOD): 1 U/ml.
– Results Interpretation: Negative: < 25 U/ml, Positive: ≥ 25 U/ml.
– Expected Values: Cut-off 25 U/ml
– Intra-Assay: 5.5 – 7.3%
– Inter-Assay: 7.5 – 9.9%
– Interference: None.
– Clinical Diagnosis: Sensitivity (96.0%), Specificity (88.8%), Overall agreement (93.4%).


  1. [Measurement and comparison of the rheumatoid factors class IgG, IgM and IgA in chronic juvenile rheumatoid arthritis]. An Esp Pediatr. (1989) 31 (6): 554-8. Review. Spanish. Alvarez García J., et al.
  2. Rheumatoid factor diversity. In Vivo. (1988) 2 (1): 73-7. Review. Koopman W.J. and Schrohenloher R.E.
  3. Autoantibodies and other serological markers in rheumatoid arthritis: predictors of disease activity? Clin Rheumatol. (2009) 28 (10): 1127-34. Review. da Mota L.M., et al.
  4. Rheumatoid factors, B cells and immunoglobulin genes. Br Med Bull. (1995) 51 (2): 312-31. Review. Jefferis R.
  5. Regulation ofrheumatoid factorsynthesis. Clin Exp Rheumatol. (1989) 7 Suppl 3: S69-73. Review. Carson D.A., et al.
  6. B lymphocyte function in patients with rheumatoid arthritis: impact of regulatory T lymphocytes and macrophages–modulation by antirheumatic drugs. Dan Med Bull. (1988) 35 (2): 140-57. Review. Petersen J.


  • Full Name: Rheumatoid Factor Screen ELISA Kit
  • Reactivity: Human
  • Sample Type: Serum, Plasma
  • Sensitivity: 1.0 U/ml



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