Differentiation of Myeloid Cells and 1, 25-Dihydroxyvitamin D3

Abstract

It is well established that1, 25(OH)2D3 induces monocyte/macrophage (Mo/Mø) colonies when added to culture of granulocyte/macrophage progenitors. Recently, we demonstrated that one of the target cells of1, 25(OH)2D3 in Mo/Mø differentiation is the neutrophilic promyelocyte that is believed to belong to the neutrophilic lineage. This fact overthrows the established theory that normal hematopoietic precursors are committed to respective cell lineages and do not deviate from their own lineage. The lineage switching from the promyelocyte to Mo/Mø was suggested to be operating in vivo because1, 25(OH)2D3 is a physiological substance produced by Mø. More recently, we have shown that transient exposure (24 h) of promyelocytes to1, 25(OH)2D3 causes Mo/Mø differentiation. This strategy could be useful for examining the effects of1, 25(OH)*D3 on the growth and differentiation of normal myeloblasts and myeloid progenitor cells. Recent advances in molecular biology have enabled investigators to identify a number of genes involved in Mo/Mø differentiation induced by1, 25(OH)2D3. Some of these may be the determinant genes for Mo/Mø differentiation; however, further studies are required to determine the underlying mechanisms of Mo/Mø differentiation.