title: Expression of functional Fas ligand in choriocarcinoma.
abstract: OBJECTIVE
  In the course of pregnancy, fetal trophoblast cells and in that of choriocarcinoma-etiology, trophoblast derived tumor cells, invade the uterine mucosa without causing rejection by decidual leukocytes. Fas ligand (FasL, CD95L, APO-IL), a central regulator of the immune system, has been implicated in the maintenance of immune privileged sites, such as the eye, the testis and the pregnant uterus by inducing apoptosis in activated infiltrating leukocytes. In normal pregnancy FasL, which is expressed by trophoblast cells, appears to contribute to the immune privilege of the pregnant uterus. As choriocarcinoma derives from trophoblast we wanted to assess the expression of FasL in this tissue.
  
  
  METHODS
  Immunohistochemistry, immunofluorescence, TUNEL-assay, Western blotting, coculture experiments and flourescence-associated cell sorter-analysis were the techniques used.
  
  
  RESULTS
  Expression of FasL was found on cells of choriocarcinoma in paraffin sections in situ and on three choriocarcinoma cell lines such as JEG-3, JAR and BeWo. These results were confirmed by Western blotting. In coculture experiments choriocarcinoma cells induced apoptosis in a Jurkat cell line - sensitive to FasL mediated killing. However, when the Jurkat cells were pre-incubated with a Fas-blocking monoclonal antibody, apoptosis was abolished to a great extent.
  
  
  CONCLUSIONS
  Our findings show that choriocarcinoma cells express FasL and this aforementioned molecule is biologically active. We assume that FasL expression on choriocarcinoma cells may contribute to control of anti-tumor responses by inducing apoptosis in activated Fas bearing leukocytes.
authors.affiliation: Institute of Histology and Embryology, Karl-Franzens-University, Graz, Austria. astrid.hammer@kfunigraz.ac.at
authors.forename: Astrid
authors.initials: A
authors.lastname: Hammer
authors.forename: Michaele
authors.initials: M
authors.lastname: Hartmann
authors.forename: Peter
authors.initials: P
authors.lastname: Sedlmayr
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Walcher
authors.forename: Gaby
authors.initials: G
authors.lastname: Kohnen
authors.forename: Gottfried
authors.initials: G
authors.lastname: Dohr
mesh_terms: D000328:Adult; D000906:Antibodies / Q000276:immunology; D017209:Apoptosis / Q000276:immunology; D015153:Blotting, Western; D002822:Choriocarcinoma / Q000276:immunology / Q000378:metabolism*; D018920:Coculture Techniques; D053222:Fas Ligand Protein; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D019169:Jurkat Cells / Q000276:immunology / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D011247:Pregnancy; D014594:Uterine Neoplasms / Q000378:metabolism
chemical_list: D000906:Antibodies; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins