IgM autoagglutinins in warm autoimmune hemolytic anemia: a poor prognostic feature.

The presence of both complete IgM autoagglutinins and IgG autoantibodies in warm autoimmune hemolytic anemia (AIHA) is an uncommon finding. Over a 6-year period, only 5 of 115 (4.1%) patients with AIHA had IgM and IgG autoantibodies. In 3 of the 5 cases, the complete IgM autoagglutinins reacted up to 30 degrees C and these patients responded well to corticosteroid or other therapies for warm AIHA. The 2 patients who had warm (37 degrees C) reactive IgM autoagglutinins, were refractory to corticosteroids, splenectomy and cytotoxic drugs, and died due to the complications of hemolytic anemia. The data in these 5 cases suggest that the thermal amplitude of the IgM antibody in these unusual AIHA cases may be predictive of refractoriness to therapy and poor clinical outcome.