Stimulatory action of Pluchea quitoc extract on the hematopoietic responseduring murine listeriosis

The importance of both granulocytes and macrophages in the response to List eria monocytogenes infection make this infection a suitable choice to inves tigate the effects of Pluchea quitoc on hematopoiesis. A significant deplet ion of bone marrow granulocyte-macrophage progenitor cells (CFU-GM) was obs erved at 48 and 72 h after intraperitoneal infection of mice with 1 x 10(4) L. monocytogenes. However, the treatment of infected animals with P. quito c ethanolic extract (250, 500 or 1000 mg/kg) given orally for 3 consecutive days prior to infection produced a stimulatory effect on myelopoiesis, res toring the number of CFU-GM to normal. This same dose-schedule also increas ed colony formation in normal mice as compared to controls. In addition, P. quitoc significantly enhanced survival of infected mice. Thus, it is proba ble that the ability of P. quitoc to induce a higher reserve of granulocyte -macrophage precursors in the bone marrow is of major significance in deter mining early resistance to infection.