Human Stem Cell Factor: Biological Effects and Receptor Expression on Myeloid Leukemia Cells

Abstract

Recently a novel hematopoietic growth has been identified and characterized that stimulates primitive mouse progenitor cells [13, 15]. This factor, termed stem cell factor (SCF), is a multipotent hematopoietic colony-stimulating factor (CSF) that acts after binding to its specific surface receptor, the protein encoded by the proto-oncogene c-kit [14, 12].The cDNA for human SCF has been cloned, expressed in mammalian cells, and the recombinant factor purified to homogeneity [15, 6]. Whereas SCF for itself has only low capacity to induce colony formation in progenitor assays in vitro (CFU-GM, BFU-E, CFU-GEMM, and CFU-L) on normal bone marrow cells, it has strong synergistic activities with other factors. It synergizes with granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF), and interleukin-3 (IL-3) in myelopoiesis [8], with erythropoietin (EPO) in erythropoiesis [8], with IL-6 in megakaryopoiesis, with IL-7 in lymphopoiesis [9], and with IL-3 in mast cell growth [7]. The aim of this study was to investigate the mitogenic potential of SCF alone or in synergy with other factors and the pattern of its receptor expression on myeloid leukemia cells.