CD40LG and autoimmune hemolytic anemia: Importantly, with AIHA, the thermal amplitude of autoantibodies also determines their clinical significance, with IgG antibodies typically being associated with reactions at body temperature (approximately 37°C) presenting with significant haemolysis and IgM typically being associated with reactions at room temperature (4°C–34°C) and therefore typically being associated with a more benign course [13].