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

Abstract

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.