Autoimmune diseases and monoclonal gammopathies.

Rheumatoid arthritis, systemic lupus erythematosus and primary Sjögren's syndrome are nonorgan-specific autoimmune diseases in which serum monoclonal immunoglobulins (MIg) have been identified repeatedly. Conversely, autoimmune traits have been detected in a number of patients with lymphoproliferative disorders such as multiple myeloma, Waldenström's macroglobulinemia and chronic lymphocytic leukemia. The latter cells have even shown to produce multispecific autoantibodies. One connection between connective tissue diseases and Iymphoid malignancies might be established by a limitedfraction of B Iymphocytes expressing the CD5 marker.