Regulation of human megakaryocytopoiesis.

Megakaryocytopoiesis is a complex, highly regulated cellular and biologic process which leads to the production of platelets. The proliferation of megakaryocyte (MK) progenitors is mainly regulated by interleukin-3, granulocyte-macrophage colony-stimulating factor and an as yet uncharacterized MK colony-stimulating factor. The maturation of MKs to produce platelets is essentially regulated by interleukin-6 and thrombopoietin. Optimal megakaryocytopoiesis is controlled by appropriate combinations of positive and negative influence. Megakaryocytopoietic inhibition is controlled by transforming growth factor beta, platelet factor 4 and its related proteins, interferon-alpha and -gamma.