Molecular physiology of granulocyte-macrophage colony-stimulating factor

EMATOPOIESIS IS A quantitatively imposing pro-H cess in the adult, where about 3 x lo9 erythroid cells/kg and lo9 myeloid celis/kg are generated each day.Twenty-five years ago, in vitro assays were developed to detect factors that could stimulate the growth of colonies from immature bone marrow (BM)-derived progenitors.'.'These systems have made it possible to identify and characterize the factors regulating myelopoiesis.The application of molecular biologic approaches to study hematopoiesis facilitated the cloning of genes encoding the hematopoietic growth factors and their production in mammalian cells, yeast, and bacteria in quantities sufficient for in vitro and in vivo studies.Granulocyte-macrophage colonystimulating factor (GM-CSF) is one of a family of glycoprotein cytokines that have potent effects in stimulating proliferation, maturation, and function of hematopoietic cells.Although GM-CSF was the first, several hematopoietic growth factors are now used in clinical trials.Most of the effects observed using GM-CSF in vitro have been shown to occur in vivo either in animal models or in human subjects.In this review, I shall summarize the basic science studies on GM-CSF, because others have recently reviewed the literature on the clinical applications of GM-CSF and other hematopoietins.'-'