title: HLA-G and its role in implantation (review).
abstract: BACKGROUND
  Human leukocyte antigen G (HLA-G) is thought to play a key role in implantation by modulating cytokine secretion to control trophopblastic cell invasion and to maintain a local immunotolerance.
  
  
  METHODS
  The literature is reviewed to provide a description of the genetic background, properties of the protein, and the function of HLA-G. Data are presented on potential clinical applications of HLA-G including the use of evaluation of HLA-G gene polymorphisms in the diagnosis of patients experiencing recurrent pregnancy loss and evaluation and testing of soluble HLA-G (sHLA-G) in embryo culture media for the selection of embryos for transfer after in vitro fertilization (IVF).
  
  
  RESULTS
  The literature supports a central role of HLA-G for successful implantation. Of couples experiencing recurrent pregnancy loss, 32% demonstrated the -1725G HLA-G polymorphism. Our data showed that when embryos were selected for transfer after IVF based on culture media concentrations of sHLA-G > or = 2 U/ml and good morphologic grade, a 65% pregnancy rate compared with a 0% pregnancy rate in those with <2 U/ml sHLA-G.
  
  
  CONCLUSIONS
  HLA-G is important for successful implantation in human beings. The HLA-G -725 promoter polymorphism is a risk factor for recurrent miscarriage. Measurement of sHLA-G in embryo culture media can help select embryos for transfer after IVF allowing fewer embryos to be transferred in an attempt to lower multiple gestation rates.
authors.affiliation: Millenova Immunology Laboratories, Chicago, IL, USA. rgroussev@yahoo.com
authors.forename: Roumen G
authors.initials: RG
authors.lastname: Roussev
authors.forename: Carolyn B
authors.initials: CB
authors.lastname: Coulam
mesh_terms: D010064:Embryo Implantation; D005260:Female; D006680:HLA Antigens / Q000378:metabolism*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate
chemical_list: D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I