ABO-incompatible allogeneic bone marrow transplantation

Objective: To explore the immunohematological problems in ABO-incompatible allogeneic bone marrow transplantation (allo-BMT).

Methods: Among 250 HLA-matched allo-BMTs, 61 were performed between ABO incompatible siblings. Out of these 61 BMTs, 38 were major ABO-incompatible and 23, minor. Control group included 61 HLA-matched Allo-BMTs with ABO compatible grafts. The major ABO incompatible patients received marrow grafts depleted of erythrocytes by hydroxyethyl starch (HES) sedimentation. The minor or bidirectional received marrow grafts depleted of plasma to reduce anti-A or anti-B agglutinins. ABO antigen and antibody in the recipients sera were determined once a week.

Results: ABO-incompatible grafts for BMT had no adverse effect on engraftment, recovery of platelets, incidence of GVHD or survival. No recipient developed clinically hemolysis during or after marrow infusion. In ABO major compatible group, the onset of erythropoiesis after BMT was delayed and more RBC transfusions were required. Five of 10 recipients with blood group "O" in this group developed pure red cell aplasia (PRCA), lasting 7-24 months. Two of them recovered without therapeutic intervention. In the PRCA patients, the RBC antibody titers remained high for a longer time after BMT than in those whose erythropoiesis reconstituted timely. Serious morbidity related to ABO incompatibility did not occur.

Conclusions: ABO-incompatible allo-BMT is fairly safe if there is indication, however, PRCA may develop in isolated cases.