CELL-KINETICS OF GM-CFC IN THE STEADY-STATE

  • 1 January 1985
    • journal article
    • research article
    • Vol. 13  (6) , 532-538
Abstract
The kinetics of cell turnover for myeloid/monocyte cells that form colonies in agar (GM-CFC) were measured through the progressive increase in their sensitivity to 313-nm light during a period of cell labeling with BrdCyd [bromodeoxycytidine]. Two components of cell killing with distinctly separate labeling kinetics revealed both the presence of 2 generations within the GM-CFC compartment and the properties of the kinetics of the precursors of the GM-CFC. These precursors of the GM-CFC were not assayable in a routine GM-CFC assay when pregnant mouse uterus extract and mouse L-cell-conditioned medium were used to stimulate colony formation but were revealed by the labeling kinetics of the assayable GM-CFC. These precursor cells appeared to enter the assayable GM-CFC population from a noncycling state. This was evidenced by the failure of the majority of these cells to incorporate BrdCyd during 5 days of infusion. The half-time for cell turnover within this precursor compartment was measured to be .apprx. 5.5 days. These normally noncycling cells proliferated rapidly in response to endotoxin. High-proliferative-potential colony-forming cells (HPP-CFC) were tested as a candidate for this precursor population. The results of the determination of the kinetics for these cells showed that the HPP-CFC exist largely in a Go state, exiting at an average rate of once every four days. The slow turnover time for these cells and their response to endotoxin challenge are consistent with a close relationship between the HPP-CFC and the Go pool of cells that is the direct precursor of the GM-CFC.