MECHANISMS OF THE GRAFT-VERSUS-LEUKEMIA REACTION

It is now clear that the graft-versus-leukemia (GVL) effect which acco mpanies allogeneic bone marrow transplantation for hematological malig nancies is a powerful therapeutic weapon which, if harnessed, could im prove our ability to treat refractory malignant disorders. Advances in the understanding of the alloimmune response now provide a clearer pi cture of the mechanisms involved in the GVL reaction: the CD4(+) T cel l plays a central role in the orchestration of leukemia cell killing. The immunogenicity of the leukemia is also a major factor determining the effectiveness of the GVL response. The characterization of antigen s restricted to leukemia and hematopoietic tissues should make it even tually possible to produce specific and powerful antileukemic alloresp onses in donor lymphocytes by adoptive immunotherapy or by vaccines.