Fatal immune hemolytic anemia following allogeneic stem cell transplantation: report of 2 cases and review of literature.

Immune hemolytic anemia is a well-recognized complication after allogeneic hematopoietic stem cell transplantation (HSCT). There are 4 possible causes for this complication. First, antibodies present in the recipient destroy donor cells. Second, donor red cell antibodies at the time of stem cell infusion are transferred to the recipient. Third, sometimes, engrafted donor lymphocytes cause active production of red cell antibodies. Fourth, another cause of hemolysis after allogeneic HSCT is autoimmune hemolytic anemia (AIHA). It is thought to be due to antibodies produced by the donor's immune system against antigens on red cells of donor origin. Autoimmune hemolytic anemia after allogeneic HSCT is rare, it is still not well characterized, and it represents a life-threatening situation. We describe 2 patients with acute myeloid leukemia treated with intensive chemotherapy and umbilical cord blood stem cell transplantation (UCBT). One patient developed AIHA at day +182 and the other at day +212 after receiving UCBT. Patients received 5 and 7 line treatment options, respectively, including continuous corticosteroids, intravenous immunoglobulin, splenectomy, cyclophosphamide, plasma exchange, rituximab, bortezomib, and eculizumab. However, both patients died because of massive hemolysis after 85 and 106 days of intensive treatment, respectively. These cases reflect the extreme difficulty in the therapeutic management of patients with AIHA following UCBT. After an extensive review of the literature, the exact physiopathologic mechanisms of AIHA after allogeneic HSCT in general, and after UCBT in particular, and therefore an effective treatment remain unknown.