Rheumatoid Factor Test: What Is It?
The rheumatoid factor (RF) is a group of proteins which are produced by various immune cells in response to tissue damage or infection. These cells include macrophages, dendritic cells, natural killer (NK) cells and T lymphocytes.
These cells are part of the innate immunity system, which helps protect against infections and other harmful substances.
The rheumatoid factor is primarily targeted at protecting the body from bacteria and other foreign invaders.
The rheumatoid factors are a group of related glycoproteins that can be found in blood, synovial fluid, and other body fluids. They are mainly used by the immune system to identify and eliminate bacterial infections or other foreign substances.
The rheumatoid factors exist in various types. The most common form of rheumatoid factor (IgG) is erythrocyte sedimentation rate (ESR). There is also another type called anti-microtubule antibody.
The rheumatoid factor test measures the presence of any of these rheumatoid factors in blood.
In most cases, the rheumatoid factors will be directed against citrullinated proteins. These proteins are found in human tissues and are not usually found in bacteria. The presence of anti-citrullinated protein antibodies is a strong indication of rheumatoid arthritis.
The rheumatoid factors are used in the laboratory to detect cases of early-stage and undiagnosed rheumatoid arthritis.
The rheumatoid factors are different from other markers of inflammation such as C-reactive protein, which indicate the presence of chronic inflammation.
The rheumatoid factors are also different from other markers of autoimmunity such as ANA, which indicate the presence of autoimmune diseases.
The rheumatoid factor test is a blood test used to detect antibodies in the blood that are directed against the body’s own cells.
Rheumatoid factors are primarily used to detect undiagnosed cases of rheumatoid arthritis. It is also used to detect the recurrence or persistence of symptoms of the disease even after treatment.
The rheumatoid factor test is a simple blood test. A small amount of blood is drawn from a vein in the arm or hand. The blood is then analyzed for the presence of rheumatoid factors.
Patients who show high levels of the rheumatoid factors are advised to undergo other tests to rule out other autoimmune diseases.
Sources & references used in this article:
- Diagnostic and prognostic characteristics of the enzyme linked immunosorbent rheumatoid factor assays in rheumatoid arthritis. (H Visser, LB Gelinck, AH Kampfraath… – Annals of the …, 1996 – ard.bmj.com)
- The latex test revisited. Rheumatoid factor testing in 8,287 rheumatic disease patients (F Wolfe, MA Cathey, FK Roberts – Arthritis & Rheumatism …, 1991 – Wiley Online Library)
- Control for rheumatoid factor in the latex test for cryptococcosis (JE Bennett, JW Bailey – American Journal of Clinical Pathology, 1971 – academic.oup.com)
- The prognostic value of the antiperinuclear factor, anticitrullinated peptide antibodies and rheumatoid factor in early rheumatoid arthritis (CH Van Jaarsveld, EJ Ter Borg… – Clinical and …, 1999 – clinexprheumatol.org)
- Detection of immune complexes. The use of radioimmunoassays with Clq and monoclonal rheumatoid factor. (A Gabriel, V Agnello – The Journal of clinical investigation, 1977 – Am Soc Clin Investig)
- The rheumatoid factor: an analysis of clinical utility (RH Shmerling, TL Delbanco – The American journal of medicine, 1991 – Elsevier)
- Study of rheumatoid factor in a normal population (M Waller, EC Toone – Arthritis & Rheumatism: Official Journal of …, 1964 – Wiley Online Library)