Rheumatoid Factor IgG ELISA Kit


The RF IgG ELISA Assay Kit is used for the quantitative determination of rheumatoid factor (RF) IgG in human serum or plasma. The Eagle Biosciences RF IgG ELISA kit is for research use only and not for diagnostic procedures.
This product was previously known as RFG31-K01.

Rheumatoid Factor IgG ELISA Kit

Rheumatoid Factor IgG ELISA Kit Developed and Manufactured by Medipan

Size: 1×96 wells
Sensitivity: 1 U/ml
Dynamic Range: 1 – 300 U/ml
Incubation Time: 2.5 hours
Sample Type: Serum, Plasma
Sample Size: 10 µL
Alternative Names: Rheumatoid Factor IgG ELISA, Human RF IgG ELISA, RF IgG
For Research Use Only

Rheumatoid Factor IgG is calibrated in arbitrary units U/ml.

Dilutions of selected positive specimens in Rheumatoid Factor IgG autoantibody free human serum are determined according to their expected theoretical values with RF IgG.

Assay Principle for Rheumatoid Factor IgG ELISA

The Rheumatoid Factor IgG ELISA Kit is an enzyme immunoassay for the quantitative determination of IgG antibodies to the Fc region of IgG in human serum or plasma.  The rheumatoid factors of the calibrators, control and diluted patient samples react with rabbit IgG immobilized on the solid phase of microtiter plates. Following an incubation period of 60 min at room temperature, unbound sample components are removed by a wash step. The bound IgG antibodies react specifically with anti-human-IgG conjugated to horseradish peroxidase (HRP). Within the incubation period of 30 min at RT, excessive conjugate is separated from the solid-phase immune complexes by the following wash step. HRP converts the colorless substrate solution of 3,3’,5,5’-tetramethyl¬benzidine (TMB) added into a blue product. The enzyme reaction is stopped by dispensing an acidic solution into the wells after 15 min at room temperature turning the solution from blue to yellow. The optical density (OD) of the solution at 450 nm is directly proportional to the amount of specific antibodies bound. The standard curve is established by plotting the antibody concentrations of the calibrators (x-axis) and their corresponding OD values (y-axis) measured. The concentration of antibodies of the specimen is directly read off the standard curve.

Related Products

Anti-CCP ELISA Assay Kit

Additional Information

Assay Background

Patients suffering from rheumatoid arthritis (RA) exhibit RF, autoantibodies recognizing the Fc part of IgG. RA or chronic polyarthritis has a yet unknown etiology and represents the most frequent rheumatic inflammatory disorder demonstrating a prevalence rate of up to 1%. One of the typical manifestations of RA is symmetric synovialitis of limb joints often accompanied by involvement of the cervical spinal column.  Beside clinical features one of the criteria of the American College of Rheumatology for the diagnosis of RA is the presence of RF (1). Up to 80 % of RA patients may demonstrate RF. RF can occur years prior to the onset of disease and RF positive apparently healthy individuals bear a 5 – 40 times higher risk to develop RA (2). However, patients suffering from other autoimmune, infectious or B-cell lymphoproliferative disorders as well as apparently healthy elderly individuals may develop RF. High concentrations of RF are often associated with a more severe disease comprising a faster destruction of joints. In addition, they are found in patients with extra-articular manifestations such as rheumatoid nodules, polyneuropathy, vasculitis or Sicca syndrome. RF may belong to the IgG, IgM or IgA isotype whereas IgM RF is the most frequent isotype to be determined in RA patients. Extra-articular manifestations seem to be associated with IgA RF. Like RF of the IgM isotype high concentrations of IgG RF seems to appear with patients suffering from more progressive erosions of joints.

Assay Procedure

  1. Bring all reagents to room temperature (18…25°C) before use. Mix gently without causing foam.
  2. Dispense 100 µl calibrators 1 – 4 (CAL 0 optionally) , 100 µl positive control (P), 100 µl diluted patient samples into the respective wells.
  3. Cover plate, incubate 60 min at room temperature (18…25°C).
  4. Decant, then wash each well three times using 300 µl  wash solution (made of B).
  5. Add 100 µl of conjugate (D) solution to each well.
  6. Cover plate, incubate 30 min at room temperature (18…25°C).
  7. Decant, then wash each well three times using 300 µl of wash solution (made of B).
  8. Add 100 µl of substrate (E) to each well.
  9. Cover plate, incubate 15 min protected from light at room temperature (18…25°C).
  10. Add 100 µl of stop solution (F) to each well and mix gently.
  11. Read the OD at 450 nm versus 620 or 690 nm within 30 min after adding the stop solution.

Typical Standard Curve

RF IgG Standard Curve


Product Manual



Hussein MS, El-Barbary AM, Nada DW, et al. Identification of Serum Interleukin-13 and Interleukin-13 Receptor Subunit Experssions: Rheumatoid Arthritis-Associated Interstitial Lung Disease. Int J Rheum Dis. 2021;24:591-598.

Product Citations