Effect of tumor-related factors on the in vivo and in vitro colony-forming ability of normal mouse marrow cells.

The effect of normal mouse marrow preincubation with Ehrlich tumor fluid (EAF) and Ehrlich tumor cell-conditioned medium (ET-CM) was investigated both on the in vivo assay for pluripotential stem cells (CFU-S) and on the in vitro assay for granulocytic-macrophagic progenitors (CFU-C). A significant reduction of the number of CFU-S was found when bone marrow cells were incubated with EAF. The morphological analysis showed a relative increase in the granulocytic type colonies besides an absolute increase in undifferentiated ones and an absolute decrease in erythroid colonies. The in vitro data show a decrease in CFU-C production, by stimulation with standard Colony Stimulating Factor (CSF), when the marrow cells are preincubated with EAF and ET-CM. When standard CAF (obtained from L-cells) is used at the higher concentrations, the CFU-C in the ET-CM treated marrow increases to the control values. EAF and ET-CM incubation also affects the CFU-C differentiation by increasing the number of pure granulocytic clones. The experimental data were discussed in order to explain an hypothesis about the activity of tumor-related factors.