Severe delayed hemolytic transfusion reaction complicating an ABO-incompatible bone marrow transplantation.

A 26-year-old, blood group O bone marrow transplant recipient experienced a severe, delayed hemolytic transfusion reaction 6 days following transplantation of marrow from his HLA-mixed lymphocyte culture - identical, blood group AB sister. The patient's pretransplant serum contained both anti-A (IgG titer = 1:128; IgM = 1:32) and anti-B (IgG = 1:16; IgM = 1:64) which was reduced by a two-plasma volume plasma exchange followed by transfusion of four units of incompatible, donor type red cells. The patient experienced no immediate adverse reaction. On the 6th posttransplant day, he became acutely dyspneic. His hematocrit dropped to 18%; the direct antiglobulin test was positive for IgG and complement; anti-A and anti-B were eluted from his red cells. His peripheral blood smear demonstrated extensive agglutination resembling a mixed field reaction. This case demonstrates that significant morbidity may be associated with major ABO-incompatible bone marrow transplantation, that the transfusion of incompatible red cells should be undertaken with extreme caution, and that efforts should be continued to develop methods of pretransplant in vitro red cell removal from the infused bone marrow.