• ABO compatibility;
  • allogeneic haematopoietic stem cell transplantation;
  • nonmyeloablative conditioning regimen;
  • pure red cell aplasia

Background and Objectives  In the setting of major ABO-incompatible allogeneic haematopoietic stem cell transplantation (HSCT), pure red cell aplasia (PRCA) is linked to the persistence of host residual plasma cells secreting antidonor isohaemagglutinins (HA) after transplantation. There are conflicting results regarding the impact of the intensity of conditioning regimen on the occurrence of PRCA after major ABO-mismatched HSCT.

Material and Methods  To address this question, we compared two cases occurring after nonmyeloablative (NMA) and myeloablative (MA) HSCT and reviewed previous cases reported in the NMA setting.

Results and Conclusions  We observed a delayed disappearance of antidonor HAs in the NMA setting, associated to a more prolonged period of red blood cells transfusion dependence than in the MA setting. In our case as in several others, the disappearance of antidonor HAs and resolution of PRCA were observed after reinforcement of the graft-versus-host effect (i.e. immunosuppression removal or donor leukocytes infusion).