Interleukin-8 and other agonists of Gi2 proteins: Autocrine paracrine growth factors for human hematopoietic progenitors acting in synergy with colony stimulating factors

We have reviewed the current knowledge on CXC chemokine interleukin-8 (IL-8 ) and human hematopoiesis, and more generally on agonists of heterotrimeric Gi2 proteins as regulators of human hematopoiesis. It appears that low dos es of IL-8, a Gi2-agonist Produced in an autocrine fashion by normal hemato poietic progenitors, mature blood cells and leukemic cells, promotes cell s urvival or/and proliferation in response to hematopoietic cytokines. More i mportantly, inactivation of the IL-8/Gi2 pathways inhibits CD34+ cell proli feration and colony formation. Similar positive effects on hematopoiesis of other, physiological or pathological, agonists of Gi2 proteins are discuss ed, as well as the molecular pathways involved and the consequences of acti vation of other G proteins (Gq, G16) by IL-8 and other Gi2-agonists.