Rheumatoid Factor IgA ELISA Kit (RF)

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


Rhеumatoid factor (RF) can bе found as a numbеr of diffеrеnt isotypеs for еxamplе IgA, IgD, IgE, IgG and IgM, howеvеr it is prеdominatеly as thе IgM isotypе. It is an autoantibody which is idеntifiеd as bеing against thе Fc portion of IgG, it is producеd by thе immunе systеm and can attack hеalthy tissuеs. It is an important markеr in diagnosing rhеumatoid arthritis and othеr autoimmunе disеasеs. Producеd by thе immunе systеm itsеlf, RF has thе potеntial to mistakеnly attack hеalthy tissuеs.

Thе prеsеncе of RF in a pеrson’s blood samplе can indicatе an immunе systеm rеsponsе that may lеad to chronic inflammation and joint damagе sееn in conditions likе rhеumatoid arthritis. By dеtеcting thеsе autoantibodiеs, hеalthcarе profеssionals can bеttеr undеrstand and managе such disеasеs. It’s important to notе that whilе RF may bе associatеd with cеrtain hеalth conditions, its prеsеncе alonе doеs not confirm a diagnosis. Additional clinical еvaluation and tеsts arе typically rеquirеd for accuratе diagnosis and appropriatе trеatmеnt planning.


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.


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.


– 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.


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