Immunohematologic complications of bone marrow transplantation.

Normal hematopoiesis depends on successful interaction between the immune system and the hematopoietic system. The special circumstances of bone marrow transplantation (BMT) give rise to a number of well-recognized adverse interactions between these two systems, which are often manifested as peripheral blood cytopenias involving one or more cell lines. These so-called immunohematologic complications of BMT may develop following allogeneic, autologous, or syngeneic transplantation, and may occur as early as the day of transplantation or as late as several years afterward. Both autoimmune and alloimmune mechanisms have been implicated. The possibility of an immunohematologic complication should be considered any time an unexpected cytopenia develops in one or more cell lines in the post-transplant period. In addition, immunohematologic complications should be anticipated, and appropriate prophylaxis administered, when there is a major or minor mismatch between the donor and the recipient in the ABO and/or Rh blood group systems. Approaches to the prophylaxis, diagnosis, and treatment of these syndromes are reviewed herein.