Monocyte Heterogeneity: Consequences for Monocyte-Derived Immune Cells

Figure 1

The origin and differentiation of peripheral blood monocytes. Monocytes are generated from hematopoietic stem cells in the bone marrow (left) and enter the blood stream (middle) in response to different microenvironmental cues. In homeostasis, classical monocytes are continuously recruited to populate DC and macrophage levels in the intestine and dermis and bone-degrading osteoclasts at the bone surface. It remains unknown whether intermediate monocytes contribute to populations of monocyte-derived immune cells in homeostasis. Nonclassical monocytes patrol the endothelium and do not contribute to the maintenance of populations of mature immune cells in physiology.