Rheumatoid Factor IgM ELISA Kit (RF)

Full Name: Rheumatoid Factor IgM ELISA Kit (RF)
Reactivity: Human
Sample Type: Plasma, Serum
Sensitivity: 1.0 IU/ml


The IgM isotype of rheumatoid factor (RF) predominates among the other isotypes, which include IgA, IgD, IgE, IgG, and others. It is an autoantibody produced by the immune system that is recognised as being against the Fc region of IgG and has the ability to assault healthy tissues. Due to its self-production, RF has the potential to mistakenly assault healthy tissues.

The presence of RF in a person’s blood sample may signal an immune response that could result in persistent inflammation and joint damage like that seen in rheumatoid arthritis. Healthcare professionals can better understand and manage such conditions by detecting these autoantibodies.


Human rheumatoid factor IgM ELISA kit is designed for detecting in-vitro quantitative amounts of IgM antibodies to anti-rheumatoid factor IgM (RF, RF-IgM, rheumatoid factor IgM) in human serum or plasma. This assay has a minimum analytical sensitivity limit of 1.0 IU/ml.


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 Fc fragments of highly purified human Immunoglobulin G coated on to microwells.
  • Calibrator A-E: Concentration ranging from 0-500 U/ml, made up from human rheumatoid factor.
  • Control Positive And Control Negative: Containing anti-rheumatoid factor in a serum/buffer matrix.
  • Sample Buffer P (5x).
  • Enzyme Conjugate: Contains anti-human IgM antibodies, HRP labelled.
  • TMB Substrate.
  • Stop Solution.
  • Wash Buffer (50x concentrated).
  • Instruction for Use.
  • Certificate of Analysis.


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


– Expected Values: Cut-off 20 U/ml
– Limit of detection (LOD): 1 U/ml.
– Results Interpretation: Negative: < 20 U/ml, Positive: ≥ 20 U/ml.
– Linearity: 97 – 112%
– Measuring Range: 0 – 500 U/ml
– Intra-Assay: 4.3 – 4.6%
– Inter-Assay: 5.9 – 8.2%
– Interference: None.
– Clinical Diagnosis: Sensitivity (91.4%), Specificity (93.5%), Overall agreement (92.1%).


  1. Mesangial glomerulopathy and IgM rheumatoid factor in rheumatoid arthritis. Nephron. (1989) 51 (1): 107-11. Pollet S., et al.
  2. Heterogeneity of IgM/IgG cryocomplexes: immunological-clinical correlation. J Rheumatol. (1975) 2 (2): 225-40. MacKechnie H.L., et al.
  3. CD5 negative IGM rheumatoid factor-B cells in B-chronic lymphocytic leukemia and benign mixed cryoglobulinemia. Leuk Lymphoma. (1992) 7 (1-2): 55-62. Review. Martin T. and Pasquali J.L.
  4. [Immunological and serological tests for diagnosis of rheumatoid arthritis: IgM-RF]. Nihon Rinsho. (2005) 63 Suppl 1: 318-21. Review. Japanese. Ishizuka S., et al.
  5. Rheumatoid factors: good or bad for you? Int Arch Allergy Immunol. (2005) 138 (2): 180-8. Review. Nowak U.M. and Newkirk M.M.
  6. IgM paraproteins. J Clin Pathol Suppl (Assoc Clin Pathol). (1975) 6: 54-64. Review. Hobbs J.R., et al.


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