Myeloid colony-forming cell kinetics in man.

To determine the half-life of circulating myeloid colony-forming cells (CFUc) in man, we studied circulating CFUc in the blood of transplant recipients after the infusion of donor marrow. The agar culture technique was used to clone peripheral blood granulocyte-monocyte progenitors. Circulating CFUc were rare before donor marrow infusion. After infusion of a large number of donor progenitor cells, there was a rapid, linear decrease in myeloid colony-forming cells in the patients' blood. The mean half-life for the circulating CFUc was 4.6 h. No correlation was noted between maximum number of circulating CFUc and the disappearance rate from the blood. A rapid increase in circulating CFUc occurred simultaneously with marrow engraftment.