In vivo Stimulatory Effects of Neopterin on Hematopoiesis
Summary The pteridine neopterin (NP) was shown to be produced by monocytes and has been known as a useful maker of immunological activation, although, the biological activity of this agent is still unclear. To elucidate the biological function of NP, the changes in the number of blood leukocyte, bone marrow and spleen hemopoietic progenitor cells after intraperitoneal administration of NP into mice were investigated. Administration of NP increased the number of blood leukocytes about 2 fold higher than that of the control at days 7 and 14. Blood films, made by smearing samples of peripheral blood, showed the increment of granulocytes in blood of NP treated animals. The number of granulocyte-macrophage progenitor cells (CFU-GM) was also increased in both bone marrow and spleen in mice with NP administration. Extensive study showed that NP stimulated the hematological recovery in bone marrow transplanted animals. All these findings suggest that NP has a stimulating activity on hemopoiesis by affecting the proliferation and differentiation of hemopoietic progenitor cells in vivo.