Inhibition of murine granulopoiesis in vitro by dexamethasone.

The effect of dexamethasone on mouse bone marrow granulocyte-monocyte precursor cells (CFU-C) was studied in vitro. Dexamethasone inhibited colony formation in the presence of maximally stimulating concentrations of colony-stimulating activity. A mean colony reduction of 55% occurred at 10(-9) M dexamethasone and inhibition was observed at concentrations as low as 10(-12)M. The dexamethasone suppression could be abrogated by progesterone. These studies provide evidence that the committed granulocyte-monocyte stem cell has a glucocorticoid receptor mechanism that when activated results in inhibition of cellular proliferation in vitro.