Immune Hemolytic Anemia—Selected Topics

Autoimmune hemolytic anemia (AIHA) is most often idiopathic. However, in recent years, AIHA has been noted with increased incidence in patients receiving purine nucleoside analogues for hematologic malignancies; it has also been described as a complication of blood transfusion in patients who have also had alloimmunization. As the technology of hematopoietic stem cell transplantation has become more widespread, immune hemolysis in the recipients of ABO-mismatched products has become better recognized. The syndrome is caused by passenger lymphocytes transferred from the donor, and although transient, can be quite severe. A similar syndrome has been observed in recipients of solid organ transplants when there is ABO-incompatibility between donor and recipient. Venous thromboembolism is a little-recognized, though likely common, complication of autoimmune hemolytic anemia (AIHA), and may in some instances be related to coexistent antiphospholipid antibodies. While AIHA is a well-documented complication of malignant lymphoproliferative disorders, lymphoproliferative disorders may also paradoxically appear as a consequence of AIHA. A number of newer options are available for treatment of AIHA in patients refractory to corticosteroids and splenectomy. Newer immunosuppressives such as mycophenolate may have a role in such cases. Considerable experience has been accumulating in the last few years with monoclonal antibody therapy, specifically rituximab, in difficult AIHA cases; it appears to be a safe and effective option.