Abstract
Cells of the Multi-CSF (IL-3)-dependent hemopoietic cell line 32D c13 formed colonies of varying size in agar cultures stimulated by Multi- CSF. Colony formation was linear with respect to cultured cell numbers; colony numbers and size increased with increasing concentrations of Multi-CSF, and 32D colonies themselves contained a high frequency of clonogenic cells. Clonogenic 32D cells died in the absence of Multi-CSF (half-life six hours), and most were unable to complete cell cycles in progress at the time of withdrawal of Multi-CSF. The concentration of Multi-CSF directly influenced the length of the cell cycle of dividing 32D cells. Purified GM-CSF, G-CSF, or M-CSF had no capacity to support the survival or proliferation of 32D cells. Colonies formed by 32D cells appear to offer a useful model for analyzing the action of Multi- CSF in controlling self-renewal by clonogenic hemopoietic cells.
