Adjuvant effect of Pluchea quitoc extract on the resistance of tumor-bearing mice by modulation of the host hematopoietic response

Progressive tumor growth is regularly accompanied by changes in the cellula r constituents of the immune system. Evidence suggests that soluble factors generated during tumor growth can affect the amount of granulocytemacropha ge progenitors. III vitro colony growth of progenitor cells may be an early indicator of the cellular changes associated with tumor growth. Pluchea qu itoc has been previously found to modulate the hematopoietic response durin g bacterial infection. This study was designed to investigate the effects o f P. quitoc on the growth and differentiation of bone marrow granulocyte ma crophage progenitor cells (CFU-GM) in Ehrlich ascites rumor-bearing mice. I n contrast to the myelosuppression developed in the tumor-bearing animals, treatment with P. quitoc ethanolic extract (250, 500 or 1000 mg/kg) for 3 c onsecutive days after tumor challenge reversibly stimulated myelopoiesis, r estoring the number of CFU-OM to normal. This same dose-schedule also incre ased colony formation in normal mice as compared to controls. In addition, P. quitoc significantly enhanced survival of tumor-bearing mice. These resu lts suggest an immunoregulatory role for P. quitoc in counteracting the tum or-induced myelopoietic suppression as well as usefulness as adjuvant treat ment of cancer.