Suppressor Cytokines and Regulation of Myelopoiesis; Biology and Possible Clinical Uses

A number of biologically active and biochemically well-characterized cytokines have been shown to have either direct or indirect suppressive activities on the proliferation/differentiation of myeloid stem/progenitor cells. This article is a brief review of the actions of some of these molecules. These molecules include H-subunit ferritin, macrophage inflammatory protein-1 alpha, the interferons-alpha, -beta, and -gamma, the tumor necrosis factors-alpha and -beta (lymphotoxin), prostaglandins, E1 and E2, inhibin, transforming growth factor-beta, and lactoferrin. I will also review the actions of other suppressor molecules, including a newly identified 8-kd molecule that has not yet been sequenced and a synthetic pentapeptide. Current information is given on the in vitro actions of these molecules together with their activity in vivo in animal models. Possibilities for their clinical use are discussed.