Pure red cell aplasia of long duration complicating major ABO-incompatible bone marrow transplantation.

In 3 of 15 consecutive patients receiving a human leukocyte antigen (HLA)-identical but major ABO incompatible bone marrow transplant (BMT), pure red cell aplasia (PRA) lasting 5 to 8 months was observed. Titers of the incompatible anti-A agglutinin before infusion of the red blood cell (RBC)-depleted BMT was very high in one, and in the usual range in two patients. Decrease of agglutinin titers during the first 4 weeks after BMT were comparable between PRA patients and those of ABO-incompatible BMT recipients with timely RBC recovery. However, in PRA patients, agglutinin titers rose again and remained elevated for 19 to 28 weeks. RBC engraftment and reticulocyte recovery ultimately occurred spontaneously and coincided with the decrease of agglutinin titers below 16. These observations indicate that PRA is antibody-dependent in this setting. Furthermore, it is conceivable that cyclosporine facilitates recipient-derived antibody synthesis after major ABO-incompatible BMT.