The various types of blood cells are produced in the bone marrow. (10 to the 11th power of them each day in an adult human). Blood cells arise from a single type of cell called a hemopoietic stem cell – an adult multi-potent stem cell.
are very rare; about one in every 10,000 bone marrow cells,
are likely attached by adherens junctions to osteoblasts lining the inner surface of bone cavities,
express a cell-surface protein designated CD34,
produce by mitosis, two kinds of progeny – more stem cells and cells that begin to differentiate along the paths leading to the various kinds of blood cells. (For instance, a mouse that has had all of his stem cells killed by radiation can besaved by a single dose of a stem cell.)
Which path is taken is regulating the need for more of that type of blood cell which is, in turn, controlled by appropriate cytokines and/or hormones.
Interleukin-7 is the major cytokine in stimulating bone marrow stem cells. These stem cells start down the ‘lymphoid’ path leading to the various lymphocytes (mostly B cells and T cells).
Some of the cytokines that drive the differentiation of the “myeloid” leukocytes are:
Erythropoietin (EPO), produced by the kidneys, enhances the production of red blood corpuscles (RBC’s).
Thrombopoietin (TPO), assisted by Interleukin -11 (IL-11), stimulates production of megakaryocytes. Their fragmentation produces platelets.
Granulocyte-macrophage colony-stimulating factor (GM-CSF), as its name suggests, sends cells down the path leading to both those cell types. One path or the other is taken.
Under the influence of the granulococyte colony-stimulating factor (G-CSF), they differentiate into neutrophils.
Further stimulated by interleukin-5 (IL-5) they develop into eosinophils.
Interleukin-3 (IL-3) participates in the differentiation of most of the white blood cells but plays a prominent role in the formation of basophils, which are responsible for some allergies.
Stimulated by macrophage colony-stimulating factor (M-CSF) the granulocyte/macrophage progenitor cells differentiate into monocytes, macrophages, and dendritic cells. (DC’s).