Rheumatoid factor

General Information

Rheumatoid factor (RF) is an autoantibody used in the diagnostics and evaluation of autoimmune diseases, particularly rheumatoid arthritis. Elevated levels may also be associated with other autoimmune, inflammatory, or infectious conditions, so results should be interpreted in conjunction with clinical findings.

Rheumatoid factor

(RF) They are a heterogeneous group of autoantibodies that have changed their properties under the influence of a virus or other agent. They are usually IgM antibodies, but can also be IgG and IgA antibodies.

RF is synthesized by plasma cells of the synovial membrane. Autoantibodies can form immune complexes with complement system proteins and other proteins. Upon entering the synovial fluid, autoantibodies are phagocytosed and destroyed by neutrophils, which induces the release of inflammatory mediators that damage the joint tissue.

Autoantibodies can also form large protein complexes that fail to phagocytose and are therefore deposited around blood vessels in the intercellular space, leading to the development of an inflammatory reaction - vasculitis.

RF is not involved in initiating the inflammatory process that causes rheumatoid arthritis, although it is likely to contribute to the aggravation and persistence of the process.

RF can appear in the body before the onset of the disease and sometimes several years before the clinical manifestations of the disease.

Depending on the presence/absence of RF, rheumatoid arthritis is divided into 2 categories: seropositive or seronegative. Seropositive patients with rheumatoid arthritis have a several times higher risk of developing erosive arthritis, with loss of joint function and extra-articular manifestations, compared to seronegative patients.

How to prepare for the test?

The test should be performed on an empty stomach.

Research material

Venous blood