Recovery of hematopoiesis after blood-group-incompatible bone marrow transplantation with red-blood-cell-depleted grafts.

Severe hemolytic transfusion reactions may complicate major blood-group-incompatible bone marrow transplantations (BMT). Probably the most appropriate way to avoid this complication is removal of the incompatible red blood cells (RBC) from the bone marrow graft. In this report we describe a method to eliminate incompatible RBCs that is based on repeated dilution of the graft with donor-and-recipient--compatible third-party erythrocytes. Four patients with ABO incompatibility and one patient with Rh-C incompatibility were transplanted using this technique. After the procedure 86 +/- 8% (mean +/- SD) of the nucleated cells, 95 +/- 14% of CFU-GM, 88 +/- 14% of BFU-e, and 103 +/- 30% of CFU-e were recovered, but only +/- 1% of the incompatible RBCs was left in the transfusate (1-3 ml). No signs of hemolysis were observed. All patients engrafted promptly. The patients with low titers of antibody had normal reticulocyte recoveries. Maturation of erythropoiesis was suppressed only when high titers of antibody were present. However, despite high antibody titers, erythroid progenitor cells (CFU-GEMM, BFU-e, and CFU-e) could be cultured from the bone marrow of the recipient after BMT. Thus, anti-A and anti-Rh-C antibodies give little, if any, inhibition of stem-cell proliferation. The method described to remove incompatible RBCs appears to be simple, safe, and--in most cases--sufficient.