Proliferation and Differentiation in Diffusion Chambers of Marrow, Blood and Spleen Cells from Patients with Chronic Myeloid Leukaemia during Chronic Phase and Blastic Transformation

Density distribution of chronic myeloid leukaemia and normal colony-forming cells in diffusion chambers (CFU-D) and agar (CFU-GM)

The density distribution in Percoll gradients of clonogenic cells forming colonies in diffusion chambers (CFU-D) or in agar culture (CFU-GM) was studied in chronic myeloid leukaemia (CML). The density distribution of CFU-GM in CML was homogeneous with peaks within 1.058-1.061 g/ml, which is slightly lower than normal. CFU-D, on the other hand, showed heterogeneous distributions both in CML and in normal controls. Two separable populations of CFU-D were recognized, one with the same or lower density than CFU-GM that formed almost exclusively neutrophilic colonies in diffusion chambers, and a second population concentrating in the density range 1.068-1.075 g/ml which primarily formed macrophage colonies. The second population contained colony-forming cells derived from both Fc-receptor positive and Fc-receptor negative precursor cells, suggesting that at least some colonies in diffusion chambers arise from Fc-receptor positive granulopoietic cells of intermediate maturity and/or monocytes. The concentration of CFU-D in peripheral blood was increased 40- to 100-fold in 2 patients currently off treatment who had increased WBC counts.

Proliferation and differentiation of normal and chronic myeloid leukaemia (CML) marrow cells in suspension cultures

Immature myeloid cells highly enriched for colony-forming cells, myeloblasts and promyelocytes were isolated in Percoll gradients (lighter than 1.065 g/ml) from patients with chronic myeloid leukaemia (CML) or normal healthy volunteers. The proliferation and differentiation of these cells were followed in suspension cultures in McCoy's medium (15% FCS) with or without the addition of 15% human placenta conditioned medium (HP-CM) over a culture period of 12-16 d. Ion-exchange chromatography and gel chromatography indicated that the proliferation-stimulating activity in HP-CM was colony-stimulating activity (CSA). In unstimulated cultures (without HP-CM), normal cells produced very few neutrophils; macrophage production dominated. CML cells, on the other hand, gave rise to neutrophils even in the absence of stimulatory factor(s). The effect of HP-CM was dependent on the initial concentration: at a 'low' (1 X 10(5)/ml) concentration, the addition of HP-CM resulted in a great increase in neutrophils, but at a 'high' (5-8 X 10(5)/ml) initial cell concentration, HP-CM gave only minimal increase in neutrophil numbers in both normal and CML cultures. These observations suggest endogenous differences between normal and CML precursors in their requirements for or responses to growth stimulatory or inhibitory factors.