title: Amnion epithelial cells, in contrast to trophoblast cells, express all classical HLA class I molecules together with HLA-G.
abstract: OBJECTIVE
  The expression of the non-classical HLA-G gene has been shown at the protein level on trophoblast-derived embryonic tissue, like the extravillous cytotrophoblast. However, the presence of HLA-G on embryoblast-derived cells is currently controversial. The amnion epithelium is an embryoblast-derived cell layer covering the amnion cavity and is the main source for the amnion fluid.
  
  
  METHODS
  The expression of HLA class I molecules was investigated by immunohistochemical, biochemical, and molecular biological methods in amnion membranes and amnion fluid.
  
  
  RESULTS
  Immunohistochemically, HLA-C and occasionally also-B molecules as well as HLA-A and/or -G molecules have been identified on amnion epithelial cells. These results were extended by Western blotting with purified amnion epithelial cells where HLA-B and/or -C, HLA-A and HLA-G antigens have been detected. As expected HLA-G mRNA was detected in amino epithelial cells. Furthermore, classical HLA molecules as well as HLA-G were found in amnion fluid.
  
  
  CONCLUSIONS
  These results show that the amnion epithelium frequently expresses classical HLA class I molecules as well as HLA-G. The expression of HLA-G antigens on amnion epithelial cells and their presence in the amnion fluid, which is continually ingested by the fetus, may be particularly relevant for the induction of peripheral tolerance.
authors.affiliation: Department of Histology and Embryology, Karl-Franzens-University, Graz, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Hammer
authors.forename: H
authors.initials: H
authors.lastname: Hutter
authors.forename: A
authors.initials: A
authors.lastname: Blaschitz
authors.forename: W
authors.initials: W
authors.lastname: Mahnert
authors.forename: M
authors.initials: M
authors.lastname: Hartmann
authors.forename: B
authors.initials: B
authors.lastname: Uchanska-Ziegler
authors.forename: A
authors.initials: A
authors.lastname: Ziegler
authors.forename: G
authors.initials: G
authors.lastname: Dohr
mesh_terms: D000650:Amnion / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D000653:Amniotic Fluid / Q000737:chemistry / Q000166:cytology; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D004847:Epithelial Cells; D004848:Epithelium / Q000737:chemistry / Q000378:metabolism; D006680:HLA Antigens / Q000096:biosynthesis* / Q000302:isolation & purification; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*
chemical_list: D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I