The B lymphocyte and antibody system. Aberrations in the rheumatic diseases

Abnormalities of B lymphocytes are present in RA including slightly reduced number of peripheral B cells, decreased numbers of T cells (in SLE), synovial infiltration of B and T cells and plasma cells, and increased quantities of B cells in the synovial fluid. Synovial tissues show deposition of immunoglobulin, complement, immune complexes, and abnormal antibodies (e.g., RF). These findings suggest but do not prove B-lymphocyte or antibody involvement in the pathogenesis of the disease. If this system is involved in the pathogenesis, it may result from hypersensitivity, through anaphylactic, cytotoxic, or immune complex reactions; or it may result from immunodeficiency, which favors an infectious disease, immune complex formation, or uncontrolled T-cell response.