Localization of the Fas-Fas ligand system in human fetal membranes

OBJECTIVE: To determine if fetal membranes might be one of the sources of Fas and Fas ligand in amniotic fluid. STUDY DESIGN: Human fetal membranes from elective cesarean section (n = 6) were fixed in paraformaldehyde. Rolls of paraffinembedded fetal membranes were cut into 5-micron sections. After blocking with horse and goat sera, sections were incubated overnight with primary antibodies followed by the appropriate secondary antibodies. Avidin-biotin complex and diaminobenzidine were used for immunoperoxidase localization. Expression of Fas and Fas ligand was read by light microscopy. RESULTS: Both Fas and Fas ligand were localized in amnion, chorion and decidual layers. In amnion, Fas and Fas ligand were expressed predominantly in epithelial cells and fibroblasts, while there was no immunostaining in the subepithelial compact connective tissue. In the chorion, the expression was mainly in the chorionic trophoblast, with inconsistent expression in the reticular layer. In the decidua, the expression of Fas and Fas ligand was less prominent than in amnion and chorion. CONCLUSION: Localization of Fas and Fas ligand in human fetal membranes suggests that fetal membranes could be one of the sources of soluble Fas and Fas ligand in amniotic fluid.