Immune hemolysis involving non-ABO/RhD alloantibodies following hematopoietic stem cell transplantation.

We report two cases of severe alloimmune hemolysis after hematopoietic stem cell (HSC) transplant resulting from an anti-Jk(a). The time course of hemolysis and Jk phenotypes of the donor and recipient in the cases reported suggest that the antibody was produced by donor-derived passenger lymphocytes. Retrospective analysis of the blood bank records of all allogeneic HSC transplant patients at Barnes-Jewish Hospital from 1994 to 1999 suggests that the incidence of alloimmune hemolysis due to incompatibilities involving non-ABO or RhD red cell antigens is very low, approximately 1%. In one patient, the duration of hemolysis was shortened significantly by performing red cell exchange at the first sign of intravascular hemolysis.