Cell kinetics of lithium-induced granulopoiesis

Lithium has been shown to be an effective inducer of granulopoiesis. The mechanism of lithium action has been shown to influence CFU-s and CFU-c proliferation, increase colony-stimulating factor (CSF) production and reduce erythropoiesis. We report here evidence to show that lithium recruits CFU-c that are not normally in the cell cycle into active DNA synthesis, as measured by hydroxyurea and tritiated thymidine suicide techniques. Furthermore, lithium action is shown to be time-dependent, since the delay addition of lithium for 5 min to normal bone marrow removes the enhancement usually seen when lithium is given at time zero. The implications of these lithium-induced effects are described.