Chemokines, chemokine receptors and hematopoiesis

Hematopoiesis during steady state conditions is regulated and finely tuned by a network of cytokines and their effects on hematopoietic stem and proge nitor cells and on accessory cells that influence the stem and progenitor c ells. Amongst the numerous cytokines implicated in this regulation are memb ers of the CC, CXC and C family of chemokines. Twenty-five chemokine member s have been demonstrated to have the capacity to suppress the proliferation of myeloid progenitor cells. Three chemokines have been implicated in the chemotaxis of these stem and progenitor cells, and one has been linked to t heir survival after growth factor withdrawal. This review focuses on the pr oliferation-suppressing, chemotaxis-induced, and cell survival effects of d ifferent chemokine family members on myeloid progenitor cells. This is plac ed in the context of what we know and don't know about the intracellular si gnaling events mediating these effects. This information and what is yet to be learned in this area could have important clinical implications for tre atment of disease.