ABSTRACT
This chapter focuses on studies to elucidate the role on myelopoiesis of biomolecules, termed cytokines, which are produced by cells from the body and which act through specific cell surface receptors to modulate cell proliferation and differentiation. The circulating myeloid elements: polymorphonuclear neutrophils, monocytes, erythrocytes, and platelets derive from a rare population of cells called hematopoietic stem and progenitor cells. Hematopoietic progenitor cells can be studied more directly after physical and immunological cell separation. Human leukemic clonogenic cells can be grown in culture, and some evidence exists for autocrine growth of primary myeloid cells from patients with leukemia. Activin and Inhibin are biomolecules that respectively enhance and suppress the release of follicle-stimulating hormone from pituitory cells in vitro.
