Rheumatoid factor (RF)

General Information

Rheumatoid factor (RF) A group of the body's own immunoglobulins 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 both 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 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 may appear in the body before the onset of the disease and sometimes several years before the clinical manifestation of the disease.

According to the presence / absence of rheumatoid factor, rheumatoid arthritis is divided into 2 categories: seropositive or seronegative. The risk of developing erosive arthritis in seropositive patients with rheumatoid arthritis, with loss of joint function and external manifestations, is several times higher than in seronegative patients.

HIV-positive patients are at high risk of developing seronegative arthritis with loss of joint function and external manifestations such as rheumatoid nodules, lung disease, vasculitis, Felt syndrome (neutropenia and splenomegaly associated with rheumatoid arthritis).

RF is not specific for rheumatoid arthritis and is also defined in other connective tissue diseases and some chronic infections (endocarditis, tuberculosis, hepatitis B).