The relationship between CD5-expressing B lymphocytes and serologic abnormalities in rheumatoid arthritis patients and their relatives

Rheumatoid arthritis (RA) is an autoimmune disorder in which the immune system and its components attack the body's own tissues and factors. This disorder is characterized by inflammation of the joints, stiffness, swelling, overgrowth of the joint cartilage, and pain. The development of the disease has been closely associated with the presence of certain genetic elements called HLA alleles. However, only a few patients show a family-based trend in the incidence of RA, and the basis for susceptibility to RA is not clear. Studies have shown that a specific type of immune cell, the CD5+ B lymphocyte, is increased in patients with RA and is important in the production of rheumatoid factor and abnormal immune proteins called autoantibodies. The relationship between expression of CD5+ B lymphocytes and autoantibodies was assessed in 12 patients with rheumatoid arthritis and 52 healthy first-degree relatives. RA patients had more CD5+ B cells than their healthy relatives and unrelated healthy subjects. However, the levels of CD5+ B cells were high in RA patients and their relatives in five of the families studied. RA patients and their relatives frequently had increased total levels of the immune proteins known as immunoglobulins, and increased levels of autoantibodies (these elevated levels were found in 20 to 40 percent of patients and 10 to 20 percent of relatives). Also, it was found that the levels of IgM-type rheumatoid factor were correlated with the proportion of B cells that expressed the CD5 molecule. (Consumer Summary produced by Reliance Medical Information, Inc.)