title: Embryonic human leukocyte antigen-G expression: possible implications for human preimplantation development.
abstract: OBJECTIVE
  To investigate further the association between human leukocyte antigen G (HLA-G) expression in human embryos and other factors known to influence IVF pregnancy outcome.
  
  
  METHODS
  A university-based tertiary referral center (The Toronto Hospital).
  
  
  METHODS
  Nontransferred embryos at the two- to four-cell stage were obtained from patients undergoing IVF and were cultured in Ham's F-10 medium supplemented with 10% human sera or cocultured with ovarian cancer cells in the same medium. Embryos that reached blastocyst stage (n = 148) were analyzed by reverse transcriptase-polymerase chain reaction for HLA-G and beta 2 microglobulin (beta 2m) expression. Statistical analysis was performed to identify possible factors associated with variability of expression.
  
  
  RESULTS
  Approximately 40% of studied blastocysts had detectable expression of both HLA-G and beta 2m messenger RNA. In 46% of blastocysts, beta 2m alone was observed. Interestingly, sibling embryos from patients that became pregnant were significantly more likely to express HLA-G than embryos from patients that did not conceive as a result of their IVF cycles. No association was found between HLA-G expression and culture conditions, patients age, or infertility diagnosis.
  
  
  CONCLUSIONS
  The population of embryos obtained through IVF is heterogeneous in expression of HLA-G and beta 2m, which may reflect overall health of the embryos. Blastocysts showing positive HLA-G expression may have increased viability and implantation potential, although the underlying mechanisms remain to be elucidated.
authors.affiliation: Department of Obstetrics and Gynecology, Toronto Hospital Research Institute, Ontario, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Jurisicova
authors.forename: R F
authors.initials: RF
authors.lastname: Casper
authors.forename: N J
authors.initials: NJ
authors.lastname: MacLusky
authors.forename: C L
authors.initials: CL
authors.lastname: Librach
mesh_terms: D001483:Base Sequence; D001755:Blastocyst / Q000276:immunology*; D046508:Culture Techniques; D047108:Embryonic Development; D005314:Embryonic and Fetal Development; D005260:Female; D005307:Fertilization in Vitro; D015870:Gene Expression; D006680:HLA Antigens / Q000235:genetics* / Q000502:physiology*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D001613:beta 2-Microglobulin / Q000235:genetics
chemical_list: D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D012333:RNA, Messenger; D001613:beta 2-Microglobulin