Cytogenetic evolution after bone marrow transplantation for chronic myeloid leukaemia.

In patients with chronic myeloid leukaemia in chronic phase treated by allogeneic transplantation using unmanipulated donor marrow cells the incidence of cytogenetic or haematological relapse is low. Occasional Ph positive metaphases have been identified in the marrow without subsequent evolution to haematological or clinical relapse. In contrast in patients transplanted with marrow depleted of T-cells Ph-positive cells are found frequently in the marrow and subsequent progression to haematological relapse is relatively common. These observations strongly support the concept of a graft-versus-leukaemia effect mediated by T-lymphocytes or by cells with a similar membrane phenotype.