Session 31: Endometriosis 1

also sensitized ESC to Fas-mediated apoptosis, but this effect seems not to be mediated by the downregulation of FLIP, an inhibitor of caspase-8 activation. Conclusion: In summary, we demonstrate that human ESC are primarily resistant to apoptotic Fas-signaling. However, the decidual NK cell-derived cytokines IFN-g and TNF-a can sensitize ESC to Fas-mediated apoptosis by an upregulation of Fas. The early embryonal signal hCG has no effect on Fasmediated apoptosis in ESC. Interestingly, both sensitizing cytokines belong to the pro-inflammatory T helper (Th)-1 family, which is thought to be harmful in implantation and pregnancy in humans. Therefore sensitivity or resistance of ESC to apoptotic Fas-stimulation could play an detrimental role for the success or failure of early implantation.