The devil is in the details: retention of recipient group A type 5 years after a successful allogeneic bone marrow transplant from a group O donor.

CONCLUSIONS: ABO-incompatible (ABOi) hematopoietic stem cell transplants (HSCTs) can present challenges in the blood bank. During transplantation, patients receive components that are ABO-compatible with both the donor graft and recipient; this practice can strain group O red blood cell (RBC) inventories.1 In addition, there are risks for acute hemolysis at the time of infusion and in the early post-transplant period.1,2 In ABO major-incompatible bone marrow HSCTs, which contain significant quantities of donor RBCs that are ABOi with recipient plasma, it is common to perform a RBC depletion of the bone marrow in an effort to minimize hemolysis at the time of infusion.2 Furthermore, patients with high-titer ABO antibodies may undergo a prophylactic, pre-transplant plasma exchange to further reduce the risk of acute hemolysis, delayed RBC engraftment, and pure RBC aplasia.2-4 ABO minor-incompatible HSCTs, in which donor plasma is ABOi with the recipient, have less risk for hemolysis at the time of infusion but can result in transient hemolysis approximately 10-21 days post-transplant, especially in patients undergoing nonmyeloablative HSCT and/or patients who have not received methotrexate for graft-versus-host-disease (GVHD) prophylaxis.1-4 In these patients, viable donor B-lymphocytes in the graft may expand and produce ABO antibodies capable of hemolyzing patient RBCs.