Transfusion policy: when to stop the use of extremely rare blood for an allogeneic hematopoietic progenitor cell transplant recipient with a history of red cell alloimmunization.

BACKGROUND Decisions for when to select, and when to discontinue, antigen-negative blood in hematopoietic progenitor cell transplantation (HPCT) recipients with red blood cell (RBC) antibodies can be confusing. In HPCT performed for sickle cell anemia patients who require extremely rare antigen-negative blood, the balance of caution and practicality is further complicated. CASE REPORTS Four sickle cell anemia patients with current or historic RBC antibodies underwent allogeneic HPC transplantation. One required extremely rare (group O D-, hr(B)-) blood. None of the antibodies caused significant hemolysis after transplant. In the case requiring rare blood, antigen-negative blood was requested after donor RBC engraftment because of incomplete donor white blood cell (WBC) chimerism. CONCLUSIONS RBC antibodies derived from a recipient of allogeneic HPCT rarely cause significant hemolysis, in contrast to the more severe picture sometimes seen with donor-derived antibodies. When donor WBC chimerism is delayed past the time of donor RBC engraftment, there can be concern for the possibility of future recipient-type antibody production. Even 100 percent donor lymphocyte chimerism is no guarantee of total host plasma cell ablation. Immunoglobulin allotyping, when informative, can suggest chimerism for several years. Recipient-type blood, when extremely rare, may not be available for that duration.