Abstract
Murine bone marrow progenitor cells that gave rise to macrophage colonies in semisolid agar were found to be more sensitive to prostaglandins of the E series (PGE) than were precursor cells of granulocytes and megakaryocytes. Macrophage colonies themselves had different sensitivities to the molecule. Precursor cells of macrophages that formed colonies in the presence of a stimulating activity from L cells (L-cell CSA) were inhibited to 50% levels by 3 x 10(-9)-M PGE. Macrophage progenitor cells, which require both L-cell CSA and rat hemolysate for colony growth, were inhibited to the same level by 3 x 10(-7)-M PGE. Other colony types (granulocytes and megakaryocytes) were sensitive to PGE only at concentrations greater than 10(-6) M. Accordingly, addition of different PGE concentrations to the culture assay should allow easy detection of precursor cells with morphologically distinct end cells. The different sensitivities to PGE of two macrophage colony types of different maturation stages indicate that PGE may provide feedback to control macrophage formation by inhibiting proliferation and differentiation of immature monocytoid cells.
