Rheumatoid factors are proteins produced by the immune system that can attack healthy tissue in the body. High levels of rheumatoid factor in the blood are often associated with autoimmune diseases like rheumatoid arthritis and Sjogren syndrome. However, rheumatoid factor can also be detected in some healthy individuals, and its presence is not exclusively linked to autoimmune disorders.
Rheumatoid factor (RF) is an immune system protein that targets healthy cells. An RF test, a blood test, helps diagnose rheumatoid arthritis. Elevated RF levels can suggest the presence of this condition.
Initially discovered in rheumatoid arthritis patients, rheumatoid factor is an autoantibody that targets the Fc portion of IgG. Various RFs can recognize different parts of the IgG-Fc. RF and IgG combine to form immune complexes contributing to the disease process, causing chronic inflammation and joint destruction in the synovium and cartilage.
A positive rheumatoid factor test indicates high levels of rheumatoid factor in the patient’s blood. First described in relation to rheumatoid arthritis in 1940, a positive rheumatoid arthritis test has long been used in diagnosing individuals with symptoms of this condition.
Approximately 80% of adults with rheumatoid arthritis have detectable rheumatoid factor in their blood. Health care professionals use the rheumatoid factor test to aid in diagnosing rheumatoid arthritis. It’s important to note that rheumatoid factor can also be present in the blood of normal individuals and those with other autoimmune conditions.
Rheumatoid factors are not exclusive to rheumatoid arthritis; they are found in various other pathologies, including autoimmune and non-autoimmune diseases. They have been detected in up to 4% of young, healthy individuals and more commonly in the elderly. Rheumatoid factors are antibodies of various isotypes and affinities directed against the Fc portion of IgG.
For more detailed information, you can refer to the following sources:
Mayo Clinic
Medical News Today
Wikipedia
RheumatoidArthritis.org
MedicineNet
American Academy of Family Physicians
NCBI Bookshelf
