POLYCLONAL PRIMITIVE HEMATOPOIETIC PROGENITORS CAN BE DETECTED IN MOBILIZED PERIPHERAL-BLOOD FROM PATIENTS WITH HIGH-RISK MYELODYSPLASTIC SYNDROMES

Myelodysplastic syndromes (MDS) form a heterogeneous group of clonal h ematopoietic disorders with unfavourable prognosis, Allogeneic bone ma rrow transplantation is the only potentially curative treatment, but r emains limited to a small subgroup of younger patients with HLA-compat ible donors. as autologous stem cell transplantation is currently bein g explored as an alternative treatment strategy for MDS, more informat ion needs to be acquired regarding the clonal nature of the progenitor cells in these autografts. Therefore, we have analyzed the clonal pat terns of highly purified hematopoietic progenitors and their mature da ughter cells in mobilized peripheral blood collections procured from f ive female patients with high-risk MDS in complete hematologic remissi on, X-chromosome inactivation patterns of flow-sorted immature (CD34()38(low), CD34(+)33(low)) and committed (CD34(+)38(high), CD34(+)33(hi gh)) progenitors were studied with the polymerase chain reaction-based HUMARA assay, In four patients, a polyclonal remission was shown in a ll stem cell subpopulations and their mature daughter cells whereas on e patient was found to remain skewed in all fractions, except T lympho cytes. This study provides strong evidence that polyclonal immature he matopoietic progenitors can be mobilized and harvested in patients wit h high-risk MDS after treatment with high-dose chemotherapy. (C) 1995 by The American Society of Hematology.