International Journal of Cell Cloning, Vol 10, 116-125, Copyright © 1992 by AlphaMed Press
Mechanisms responsible for size differences between hemopoietic colonies: an analysis using a CSF-dependent hemopoietic cell line
D Metcalf
Cancer Research Unit, Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.
Cells of the colony stimulating factor (CSF)-dependent continuous
hemopoietic cell line 32Dcl-3 generate strikingly different large, medium
and small colonies in semisolid cultures. Reculture of cells from such
colonies showed that all colony types contained clonogenic cells able again
to form colonies of all three size types. Clone mapping showed that late
initiation of colony formation did not account for the final size
difference between colonies, a conclusion confirmed by mapping studies on
normal CSF-stimulated murine granulocyte- macrophage colonies. Clonogenic
cells within 32 D Clone 3 (32Dcl-3) colonies varied in quantitative
responsiveness to CSF stimulation. This responsiveness was generally lower
than that of the initiating clonogenic cell and was higher with cells from
small colonies than with cells from corresponding large colonies. The data
eliminated differences in intrinsic proliferative potential, cellular
hierarchy, cell cycle times or responsiveness to CSF stimulation as an
adequate explanation for colony size differences. Colony size differences
may possibly arise from random differences in the sequence of self-
generative versus differentiative divisions in clonogenic cells in
developing clones.
