Rheumatoid Factor IgM ELISA Kit


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.


Rheumatoid factor (RF) was first discovered in rheumatoid arthritis, it is mainly found as the isotype IgM but it can also be in IgA, IgD, IgE and IgG form. RF is found as an antibody directed against the Fc portion of IgG, however, there are many different RFs proteins which are able to attach to specific sections of the IgG-Fc molecule. Rheumatoid factors are useful diagnostic markers for individuals that are suspect for rheumatoid arthritis or any other related autoimmune conditions.


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.


– Rheumatoid Factor IgM (RF-IgM): ELISA
– 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.


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



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