DEMONSTRATION OF THE EXPRESSION OF CD95 LIGAND TRANSCRIPT AND PROTEININ HUMAN PLACENTA

Tolerance of the fetal allograft enables the human conceptus to implan t itself into the maternal uterus and survive and grow there. This tol erance phenomenon remains largely obscure, notably because it appears to be controlled by multiple mechanisms. CD95 ligand (CD95-L), which c an trigger death of CD95-positive cells by apoptosis, may participate in inducing anti-fetus-sensitized CD95-positive T lymphocytes to enter apoptosis. Using immunohistochemistry (first trimester and term place ntae), FAGS assays (term placenta) and RT-PCR assays (term placenta), the presence of CD95-L protein and mRNA has been shown in crude placen tal tissue preparations and isolated placental cells. Among the latter , CD95-L expression was detected in trophoblastic cells, fetal blood c ells (mRNA only) and also the Hofbauer macrophages. No CD95-L was dete cted in fibroblasts or fetal endothelial cells. Thus trophoblastic cel ls, Hofbauer macrophages, and perhaps also fetal blood cells could for m a sequential barrier blocking maternal activated defence cells beari ng CD95 molecules. (C) 1998 W. B. Saunders Company Ltd.