Lineage Commitment of Hemopoietic Progenitor Cells in Developing Blast Cell Colonies: Influence of Colony-stimulating Factors

In clonal cultures of normal mouse marrow cells, combination of granulocyte, granulocyte-macrophage, or multipotential colony-stimulating factor (G-CSF, GM-CSF, or multi-CSF, respectively) with stem cell factor (SCF) did not alter the number of blast colonies stimulated to develop compared with SCF alone but induced an up to 25-fold increase in their mean cell content and an up to 6-fold increase in their mean progenitor cell content. Costimulation of blast colony formation by SCF plus G-CSF did not change the relative frequency of progenitor cells of different types within the colonies compared with colonies stimulated by SCF alone. However, combination of GM-CSF or multi-CSF with SCF significantly increased the relative frequency of granulocytic progenitors and, for multi-CSF, also of eosinophil progenitor cells. These changes in the relative frequencies of progenitor cells committed to the various lineages support the hypothesis that hemopoietic regulators have some ability to induce selective lineage commitment in the progeny of multipotential cells.