Which antigen to use in the detection of rheumatoid factors? Comparison of patients with rheumatoid arthritis and subjects with 'false positive' rheumatoid factor reactions

Clin Exp Immunol. 1989 Sep;77(3):349-55.


In the search for differences between rheumatoid factors (RF) in patients with rheumatoid arthritis (RA) and in non-rheumatoid subjects, the reactivity of IgM- and IgA-class RF with rabbit IgG (rIgG) and Fc fragments of rabbit and human IgG (rFc, hFc) was studied by enzyme immunoassay. From a community-based cohort (n = 7124) representing the adult population of Finland, RA patients (n = 130), other subjects positive in the Waaler-Rose (WaRo, sensitized sheep cell agglutination) test (n = 137), and controls matched for age, sex and living area were selected for further study. In RA sera there was a good correlation between the results in the WaRo test and in the IgM-RF ELISA (rIgG, rFc and hFc). A considerable number of 'false positive' sera, though positive in the WaRo test and the rIgG-ELISA, were negative in the rFc-ELISA. Twenty-two per cent of the false positive sera reacted with either hFc or rFc, both types being equally common. IgA-RF reacted more frequently with hFc than with rFc in both the RA and the 'false positive' sera. In some sera, IgM- and IgA-RFs reacted differently with human and rabbit Fc, e.g. IgM-RF reacted only with human Fc, and IgA-RF reacted with both hFc and rFc, thus suggesting different regulation of their formation.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens / immunology*
  • Arthritis, Rheumatoid / immunology*
  • False Positive Reactions
  • Humans
  • Immunoglobulin A / analysis
  • Immunoglobulin Fc Fragments / immunology*
  • Immunoglobulin G / immunology*
  • Immunoglobulin M / analysis
  • Rheumatoid Factor / analysis*
  • Rheumatoid Factor / classification
  • Rheumatoid Factor / immunology


  • Antigens
  • Immunoglobulin A
  • Immunoglobulin Fc Fragments
  • Immunoglobulin G
  • Immunoglobulin M
  • Rheumatoid Factor