Effect of myleran on murine hemopoiesis. III. Changes in the density distribution of spleen colony forming (CFU-S) and agar gel colony forming cells (CFU-C).

Spleen colony forming cells (CFU-S) and agar-gel colony forming cells (CFU-C) are separate but heterogeneous cell populations, as measured by buoyant density. Myleran (MY) abrogated the major (lighter density) components of the CFU-S and CFU-C compartments, thus shifting the surviving CFU-S and CFU-C density profiles into the higher density region. The normal spleen colony erythrocytic : granulocytic (E:G) ratio profile showed three density regions with different distributions of erythroid and granulocytic colonies. The preponderantly erythrocytic colony-generating CFU-S of the intermediate density regions were eradicated by MY. Comparison of the density distribution of erythrocytic and granulocytic colony-generating CFU-S of normal bone marrow showed that the erythrocytic CFU-S profile paralleled that of total CFU-S, while most of the granulocytic CFU-S were contained in the major (and lowest density) peak. MY eradicated the two main (and lowest density) peaks of CFU-S; surviving CFU-S occurred preponderantly in a minor (higher density) peak which has a high potential for generating erythrocytic colonies.