REGULATION OF HEMATOPOIESIS

Hematopoiesis is regulated by a tiny population of cells, the stem cel ls and committed progenitors. These cells are under life influence of hematopoietic growth factors most of which are produced immediately in their environments. Their fates are strongly influenced by those grow th factors. The growth factors interact with specific receptors that a re present on progenitor surfaces and may in fact induce changes in th e levels of those receptors. The receptors form dimers or heterodimers to pass proliferative and differentiation signals into the cell. We d o not yet know exactly how that signalling is accomplished, but will p robably know much more about it in the next year or so.