13-cis retinoic acid augments the production of macrophages in mouse bone marrow cultures stimulated with interleukin 3.

Mouse bone marrow cells in liquid culture with interleukin 3 generate nonadherent granulocytes, mast cells, and macrophages. The addition of 13-cis retinoic acid (13cRA) (10(-8)-10(-6) M) enhanced proliferation of the nonadherent cells, and concentrations greater than 5 x 10(-7) M stimulated a sixfold increase in adherent macrophages. Four-color flow cytometry was used to identify the lineages present using the following antibodies: MAC1 (granulocytes and macrophages), F4/80 (macrophages), B54.2 (mast cells), and H12 (anti-Thy1.2 to identify myeloid precursors). This analysis demonstrated a twofold increase in MAC1+ F4/80+ cells, which were sorted and identified morphologically as macrophages. 13cRA also increased by 60%-95% the numbers of colony-forming cells responsive to interleukin 3 (IL-3) and macrophage colony-stimulating factor (M-CSF) but did not significantly change the colony-forming cells responsive to granulocyte-macrophage colony-stimulating factor (GM-CSF). These data suggest that 13cRA increases the production of macrophages by modulating the commitment of IL-3-expanded progenitor cells to the macrophage lineage.