Quality of IL-3 and G-CSF-mobilized peripheral blood stem cells in patients with early chronic phase CML

Coexistence of Philadelphia chromosome (Ph)-negative, primitive hematopoietic progenitor cells with their malignant counterparts in chronic myelogenous leukemia (CML) has been reported. As most of the Ph-negative progenitor cells do not express the HLA-DR antigen, selection of them might be possible. Peripheral blood progenitor cells (PBPC) from eight early chronic phase (CML) patients were mobilized by ICE chemotherapy followed by simultaneous administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and recombinant human interleukin 3 (rhIL-3). PBPCs were collected by leukapheresis in the early phase of hematopoietic recovery after chemotherapy, CD34 selected and cultured in vitro. The content of Ph chromosome-positive cells in leukapheresis products as well as after CD34 enrichment and after in vitro culture was analyzed by interphase fluorescence in situ hybridization (FISH) and RT-PCR. The percentage of Ph chromosome-positive PBPC was reduced after each purification step in almost all samples. A substantial number of PBPC samples were negative for the bcr/abl mRNA rearrangement as analyzed by RT-PCR. The present study demonstrates the feasibility of mobilizing Ph-negative PBPC during the early phase of hematopoietic recovery after ICE chemotherapy and simultaneous administration of rhIL-3 and rhG-CSF.