Rheumatoid factor refers to antibodies that are produced by the human immune system to antigens found on the tissues of the joint membranes. The production of the antibodies in question is a feature of arthritis or an autoimmune disease. In fact, this protein is synthesized by B cells under the influence of T lymphocytes. Immunity triggers the appearance of rheumatoid factor during prolonged inflammation and under its influence inflammation is reproduced in the body. This immunoglobulin has a defect. Due to its properties, it does not fulfill its main function, but destroys normal tissues of the body. Using the rheumatoid reaction, the degree of development of rheumatoid arthritis is determined.