Rheumatoid factor

Rheumatoid factor (RF) is an autoantibody of class A, G, M, which is synthesized by plasma cells of the synovial membrane. From the synovial membrane, rheumatoid factor enters the systemic bloodstream and interacts as an autoantigen with the body's own IgG. The resulting immune complexes damage the synovial membrane and blood vessel walls. The rheumatoid factor test is used to diagnose autoimmune and other inflammatory diseases. Slight increases in rheumatoid factor values are of little diagnostic value.