Autoimmune haemolytic anaemia with the unusual combination of both IgM and IgG autoantibodies

Two patients with autoimmune haemolytic anaemia of no obvious aetiology are presented. Both cases had IgM autoantibodies which were cold agglutinins with anti-I specificity and were complement binding. Both cases also had IgG autoantibodies which were incomplete, of wide thermal range and also had anti-I specificity, but were not complement binding. The red cells of both patients were coated with C4/C3d and IgG.