Stimulation of human myelopoiesis by leukotriene B4

Cultivation of human mononuclear bone marrow cells for 10 days in the presence of leukotriene B4 (8 X 10(-8) - 3 X 10(-6)M) led to an increase in the formation of granulocyte-macrophage colonies. The increase varied between 19 and 122% when compared to control cells. 5S, 12S-Dihydroxy-6, 8, 10, 14-eicosatetraenoic acid (5S, 12S-DHETE), an isomer of leukotriene B4, did not stimulate colony formation. Preincubation of the cells with 5S, 12S-DHETE inhibited the stimulatory action of leukotriene B4 on the proliferation of bone marrow cells. The present study indicates that leukotriene B4 amplifies the stimulation caused by the colony stimulating factor(s) and may play a role in modulating granulocyte and macrophage poiesis by a positive feedback mechanism.