Leukemia inhibitory factor enhances mast cell growth in a mast cell/fibroblast co-culture system through Stat3 signaling pathway of fibroblasts

Leukemia inhibitory factor (LIF) enhanced mast cell growth in a mast cell/3 T3 fibroblast co-culture system, however the precise mechanisms have not be en defined. Western blot analysis showed that bone marrow-derived mast cell s failed to express both LIF receptor (LIFR) and gp130, whereas 3T3 fibrobl asts expressed both LIFR and gp130. This result indicates that the activity of LIF for mast cell growth is mediated by 3T3 fibroblasts. Signal transdu cer and activator of transcription (Stat) 3-transfected 3T3 fibroblasts enh anced mast cell growth. In addition, dominant-negative Stat3-transfected fi broblasts blocked LIE-mediated mast cell growth in the co-culture system. I n conclusion, LIF-induced mast cell growth in the co-culture system is medi ated by an indirect pathway via 3T3 fibroblasts through activating Stat3 si gnaling pathway in 3T3 fibroblasts. (C) 2000 Federation of European Biochem ical Societies. Published by Elsevier Science B.V. All rights reserved.