Persistence of non clonal hematopoietic progenitor cells in blastic phase chronic myelogenous leukemia (CML). Working Party on Severe Aplastic Anemia (WPSAA) of the European Group of Bone Marrow Transplantation (EBMT).

Normal and clonal hematopoietic progenitor cells have been demonstrated to coexist in chronic-phase chronic myelogenous leukemia (CML), but few data are available on the presence of non neoplastic hematopoiesis during the blastic transformation phase. We used reverse transcription-polymerase chain reaction (RT-PCR) to investigate expression of the BCR/ABL transcript of individual hematopoietic progenitors from a CML patient in blastic phase. We demonstrate that non clonal hematopoiesis is induced to re-emerge by conventional chemotherapy containing fludarabine. In addition, we confirm that some pluripotent CD34+/CD33-/DR- cells circulating in the peripheral blood are not clonal. Our data provide an encouraging basis for further studies of in vitro purification of normal hematopoietic stem cells in advanced stage CML and of their use in the context of autologous bone marrow transplantation.