Multiple autoantibody production in a patient with splenic lymphoma.

We report on a patient with splenic lymphoma of B-cell origin who developed autoimmune hemolytic anemia (AIHA). IgMλ M-protein, IgM anticardiolipin antibody (ACA), and lupus anticoagulant (LA) were detected in the serum, and direct Coombs' test showed autoantibodies of the IgG1 and IgG2 subclasses on red blood cells (RBC). In in vitro culture, tumor cells isolated from the spleen produced only IgM ACA, which was enhanced by IL-6 but not by IL-4 or IL-5. The levels of ACA and LA decreased after splenectomy and chemotherapy; the strength of the direct Coombs' test, however, did not change. These findings indicated that in this patient the lymphoma cells produced IgMλ. ACA, but not autoantibodies of the IgG1 and IgG2 subclasses against RBC. It was also suggested that IL-6 might at least partially stimulate the production of ACA.