CSF3 and infection: HSC behaviors such as self-renewal, proliferation and mobilization are tightly orchestrated by cell intrinsic and extrinsic factors, the latter of which includes secreted factors and cell–cell interactions within the bone marrow (BM) niche.14, 15, 16 Granulocyte colony-stimulating factor (G-CSF) is a potent cytokine that induces HSPC proliferation, mobilization and promotion of granulopoiesis.17, 18 Many infections trigger stressed granulopoiesis through the production of G-CSF to augment granulocyte differentiation.