rheumatoid factor

https://doi.org/10.1351/goldbook.13652
Immunoglobulins IgM, IgG, and IgA autoantibodies to the Fc region of IgG.
Note: Although detectable in various diseases, rheumatoid factor is used as a classification criterion of rheumatoid arthritis (RA).
Source:
PAC, 2012, 84, 1113. (IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)) on page 1241 [Terms] [Paper]