Allogeneic Bone‐Marrow Transplantation

Over the past 12 years, marrow tranplantation has been used with increasing success for the treatment of children with immunodeficiency diseases and patients with severe, aplastic anemia, leukemia and, more recently, genetic disorders of hematopoiesis. The underlying concept of marrow transplantation is simple. Toxieity to the marrow is a serious limitation of cancer therapy in patients with leukemia. Rescue by marrow transplantation allows the use of higher and potentially curative doses of chemoradiotherapy than would otherwise be possible. In the case of patients with aplastic anemia, the grafted marrow serves to repopulate the empty marrow spaces and to repair the patient's defective production of blood cells, usually following non-lethal conditioning of patients by immunosuppressive drugs. The present review will summarize the clinical results and address questions regarding mechanisms of graft rejection, the nature of the reaction of transplanted lymphoid cells against the tissues of the host (graft-versus-host disease [GVHD]), the nature of stable chimerism observed in healthy, long-term survivors, mechanisms of leukemic relapse and of eradication of leukemia in patients who are cured, the role of putative, leukemia-associated antigens and a graft-versus-leukemia effect, the nature of immunologic deficiency following transplantation, the process of immunologic reconstitution, and the origin and management of opportunistic infections, particularly cytomegalovirus infections, in transplant recipients.