Antigen-induced Proliferation <em>in vitro</em> of Bone Marrow Precursors of Granulocytes and Macrophages.

The injection of polymerized flagellin into C57BL mice increased the number of granulocyte cluster-forming cells and macrophage colony-forming cells in the bone marrow. The addition of polymerized flagellin to agar cultures of bone marrow cells from normal or antigen-injected mice increased the number and growth rate of macrophage colonies developing when mouse serum was used as the source of colony stimulating factor (CISF). Polymerized flagellin had no potentiating effect on colony growth when urine or medium conditioned by bone marrow, spleen, lymph node or thymic cells were used as the source of CSF. Antigens may stimulate the proliferation of granulocyte and macrophage precursor cells by an indirect mechanism involving the production by bone marrow cells of CSF, or a similar growth promoting factor. [ABSTRACT FROM AUTHOR]