Immunoglobulin M rheumatoid factor (IgM RF)

Immunoglobulin M rheumatoid factor (IgM RF) is an autoantibody of the IgM class that targets the Fc region of immunoglobulin G (IgG). It is most commonly associated with rheumatoid arthritis, where it forms immune complexes with IgG that contribute to chronic inflammation and joint damage. While "rheumatoid factor" can refer to autoantibodies of various immunoglobulin classes, the term typically refers to the IgM isotype, which predominates in clinical testing. The presence of IgM RF serves as a diagnostic and prognostic biomarker for several autoimmune diseases but does not represent a therapeutic target such as a receptor or enzyme. Instead, it reflects underlying B cell dysregulation and autoreactivity[2][4][5][6]. High levels are most often linked to autoimmune disorders like rheumatoid arthritis and Sjögren syndrome but may also be found in some healthy individuals or those with infections or other inflammatory conditions[6][8]. Note: This entry should be marked as "is_incorrect = true" because "IgM rheumatoid factor" describes an antibody subtype rather than a canonical molecular target suitable for drug development; it is not itself a receptor, enzyme, transporter, or similar entity.

Other names

Rheumatoid factor (RF)IgM rheumatoid factorRF-IgMRheumatoid factor IgM isotype