granulocyte-macrophage colony-stimulating factor

(GRAN-yoo-loh-SITE-MA-kruh-FAYJ KAH-luh-nee-STIM-yoo-LAY-ting...) A substance that helps make more white blood cells, especially granulocytes, macrophages, and cells that become platelets. It is a cytokine that is a type of hematopoietic (blood-forming) agent. Also called GM-CSF and sargramostim.