Several hematopoietic growth factors (HGFs) have achieved widespread clinical
application. In the United States alone, more than US $5 billion per year of the health care
budget is spent on these factors. The first patients were treated with recombinant human
erythropoietin (rHuEPO, epoetin alfa, Epogen®) in 1985 and the first patients received
recombinant methionyl human granulocyte colony-stimulating factor (r-metHuG-CSF,
filgrastim, Neupogen®) or recombinant human granulocyte-macrophage colonystimulating
factor (rHuGM-CSF, sargramostim, Leukine® or Prokine®) in 1986.
Transfusion of granulocytes has no role in the management of febrile neutropenia, owing to their exceedingly short half-life, mechanical fragility, and clinical syndromes of pulmonary compromise with leukostasis after their use. Instead, colony-stimulating factors (CSFs) are used to augment bone marrow production of PMNs.
Megakaryocytopoiesis and platelet production depend upon thrombopoietin and its receptor, Mpl. As in the case of early erythroid and myeloid progenitor cells, early megakaryocytic progenitors require the presence of interleukin 3 (IL-3) and stem cell factor for optimal proliferation in addition to thrombopoietin. Their subsequent development is also enhanced by the chemokine stromal cell–derived factor 1 (SDF-1). However, megakaryocyte maturation and differentiation require thrombopoietin.