Apoptosis role of FAS/FAS ligand system in the regulation of myelopoiesis.

OBJECTIVES: CD34+ cells and colony forming unit-granulocyte and macrophage (CFU-GM) from human bone marrow were used to investigate the role of Fas/FasL system in the regulation of myelopoiesis. METHODS: Fas and FasL expression in CD34+ cells and in day 14 CFU-GM were measured by RT-PCR and immunofluorescence respectively. The functional assays for the CFU-GM were measured by a standard colony assay and the proliferative capacity of CFU-GM was measured by replating the primary colony and observing the secondary colony formation. Human marrow cells were treated with IETD (caspase-8 inhibitor) or anti-Fas CH-11 Mab. RESULTS: Treatment with the CFU-GM with IETD significantly increased, the proliferative capacity, while anti-Fas CH-11 Mab markedly reduced it. Fas and FasL expression were demonstrated using RT-PCR and immunofluorescence respectively. CONCLUSION: Fas, FasL, and caspase activation are likely to play an important role in the regulation of myelopoiesis.