| Abstract: | Cells which give rise to granulocyte-macrophage colonies under the influence of peripheral blood white cells (CFU-c (WBC] and Mo T cell conditioned medium (CFU-c (Mo] sedimented at a faster rate than the cells which form mixed erythroid-granulocytic colonies in methylcellulose in vitro (CFU-mix) and granulocytic (CFU-dg) and megakaryocytic (CFU-dm) colonies in diffusion chambers in mice. Despite identical peak sedimentation rate for the two CFU-c populations, sedimentation profiles suggest that they are heterogeneous with respect to size. A proportion of CFU-c (Mo) may be identical with CFU-dg and CFU-mix. Sedimentation profiles for cells which give rise to mixed colonies in vitro (CFU-mix) and to granulocytic colonies in diffusion chambers in cyclophosphamide pretreated mice (CFU-dg (CY] and in Mo conditioned medium treated mice (CFU-dg (Mo] were similar. On the average CFU-dm sedimented somewhat slower than CFU-dg. These and other observations suggesting a close relationship between CFU-dg and multipotential haemopoietic precursors are discussed. |
