Normal primitive haemopoietic progenitors are more frequent than their leukaemic counterpart in newly diagnosed patients with chronic myeloid leukaemia but rapidly decline with time

We carried out studies to quantify Ph-negative progenitors both in steady state and during regeneration after chemotherapy and G-CSF in 23 newly diagnosed chronic myeloid leukaemia (CML) patients (group A) and in 14 individuals more than a year from diagnosis (nine in chronic and five in accelerated phase, group B). In steady-state bone marrow, Ph-negative long-term culture initiating cells (LTC-IC) and Ph-negative colony-forming-cells (CFC) were detected in 18/23 and 14/23 patients of group A versus 3/14 and 3/14 patients of group B (P<0.001 and P<0.02, respectively). The absolute number of mobilized Ph-negative progenitors was markedly higher in group A versus group B (P<0.02 for LTC-IC, P<0.003 for CFC). 12/16 newly diagnosed patients mobilized Ph-negative LTC-IC only and the yield was in the range of normal allogeneic donors. Overall the frequency of Ph-negative LTC-IC in the bone marrow predicted the yield of Ph-negative LTC-IC mobilized into peripheral blood (P