Graft-versus-leukemia reactions in clinical bone marrow transplantation

Immunologic reactions occurring after allogeneic bone marrow transplantation, known as graft-versus-leukemia effect, contribute significantly to the control of minimal residual disease and decreased risk of relapse post-transplant. Graft-versus-leukemia reactions occur with or without graft-versus-host disease and are either mediated through T-cells or are independent of T-cells. The contribution made by graft-versus-leukemia reactions to improvement in overall survival depends upon the underlying type of leukemia, the nature of the marrow graft and the morbidity of any associated graft-versus-host disease. This article reviews the evidence demonstrating graft-versus-leukemia effect in clinical bone marrow transplantation, some approaches to dissociate graft-versus-leukemia from graft-versus-host disease, and attempts to induce graft-versus-leukemia reactions in the setting of autologous bone marrow transplantation by immunotherapy.