Final answer:
M-CSF stimulates the bone marrow to produce monocytes, which are white blood cells that become macrophages crucial for the immune response.
Step-by-step explanation:
Monocyte CSF (M-CSF) acts on the bone marrow (BM) and stimulates the production of monocytes. Monocytes are a type of white blood cell that circulate in the blood and lymph. Once they move into infected tissue, they differentiate into macrophages, which are crucial for the immune response. M-CSF is a type of colony-stimulating factor (CSF), a category of cytokines that also includes granulocyte CSF (which leads to the production of neutrophils, eosinophils, and basophils) and multi-CSF (which stimulates production of granulocytes, monocytes, platelets, and erythrocytes). Synthetic forms of these CSFs are administered to chemotherapy patients to help replenish their white blood cell counts.