Rheumatoid Factor IgA ELISA Kit


Human rheumatoid factor IgA ELISA kit is intended for detecting in-vitro quantitative levels of IgA antibody to rheumatoid factor (RF, RF-IgA, anti-rheumatoid factor IgA) using human plasma or serum samples. This assay has a minimum analytical sensitivity limit of 1.0 U/ml.


Rheumatoid factor (RF) is an auto-antibody that is produced by the immune system which can attack healthy tissues in the body, it was first identified in rheumatoid arthritis. Although it is predominantly encountered as IgM, rheumatoid factor be found as any of the immunoglobulins isotypes for example IgM, IgG, IgA, IgE and IgD. It is essentially characterised as an antibody against the Fc portion of IgG, there is evidence that different RFs have the ability to recognise different parts of the IgG-Fc. Rheumatoid factor and IgG are able to join and form immune complexes which are contributing to the disease process. RF is most often used to evaluate patients that are suspected of having a form of arthritis and with the combination of signs or symptoms, it can be used for diagnosis and the disease prognosis.


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, 15, 50, 150, 500 U/ml, made up from anti-rheumatoid factor in a serum/buffer matrix.
  • Control Positive And Control Negative: Containing rheumatoid factor.
  • Sample Buffer P (5x).
  • Enzyme Conjugate: Contains anti-human IgA antibodies, HRP labelled.
  • TMB Substrate: Tetramethylbenzidin.
  • Stop Solution.
  • Wash Buffer (50x).
  • Instruction for Use.
  • Certificate of Analysis.


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


– Rheumatoid Factor IgA (RF-IgA): ELISA
– Limit of detection (LOD): 1 U/ml.
– Expected Values: Cut-off 20 U/ml for samples from healthy blood donors.
– Results Interpretation: Negative: < 20 U/ml, Positive: ≥ 20 U/ml.
– Measuring Range: 0 – 500 U/ml
– Linearity: 88 – 119%
– Intra Assay Precision: 5.3 – 7.2%
– Inter Assay Precision: 5.8 – 7.8%
– Interference: None.
– Clinical Diagnosis: Sensitivity (77.8%), Specificity (92.9%), Overall agreement (83.2%).


  1. What about IgA rheumatoid factor in rheumatoid arthritis? Ann Rheum Dis. (1998) 57 (1): 63-4. Review. Jónsson T. and Valdimarsson H.
  2. Rheumatoid factors and anticyclic citrullinated peptide antibodies in pediatric rheumatology. Curr Rheumatol Rep. (2008) 10 (2): 156-63. Review. Syed R.H., et al.
  3. IgA in Sjögren’s syndrome. Clin Exp Rheumatol. (1994) 12 (5): 543-51. Review. Levy Y., et al.
  4. Clinical and biological polymorphism of rheumatoid arthritis. Clin Exp Rheumatol. (1994) 12 Suppl 11: S59-61. Review. Sany J.
  5. IgA rheumatoid factor as predictor of disease activity. Scand J Rheumatol Suppl. (1988) 75: 233-7. Review. Teitsson I.


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



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