Analysis of HLA-G in maternal plasma, follicular fluid, and preimplantation embryos reveal an asymmetric pattern of expression.
Soluble HLA-G (sHLA-G) secretion by human preimplantation embryos in culture has been associated with successful embryo development, and therefore has potential to serve as a noninvasive marker of embryo viability. We have examined the spatial and temporal expression of HLA-G in embryos of varying developmental competence and the role of maternal factors in human embryonic HLA-G expression. Embryos that reached blastocyst stage on day 5 showed a higher frequency of sHLA-G secretion than those at morula or arrested stages (p < 0.05). There was no significant difference in sHLA-G secretion between normal embryos and those diagnosed as chromosomally abnormal by preimplantation genetic diagnosis. HLA-G detected in maternal plasma and follicular fluid did not appear to correlate with HLA-G expressed in the embryo or embryo supernatants. Confocal microscopy analysis indicated that HLA-G protein expression in embryos was not homogeneous; mostly, it was confined to blastocysts localized on trophectoderm and trophectoderm projections. Single-particle fluorescent imaging analysis of HLA-G on the cell surface of JEG-3 cells showed that HLA-G particles were mostly monomeric, but dimeric and higher order oligomers were also observed. These results suggest that HLA-G play an important role in preimplantation embryo development. However, the observed expression of HLA-G in arrested and chromosomally abnormal embryos indicates that HLA-G testing should be used with caution and in conjunction with conventional methods of embryo screening and selection.
Shaikly
Valerie R
VR
Department of Biological Sciences, University of Essex, Essex, United Kingdom.
Morrison
Ian E G
IE
Taranissi
Mohamed
M
Noble
Clare V
CV
Withey
Anna D
AD
Cherry
Richard J
RJ
Blois
Sandra M
SM
Fernández
Nelson
N
D001755:Blastocyst / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D002474:Cell-Free System / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D046149:Embryo Culture Techniques; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D006680:HLA Antigens / Q000032:analysis* / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000032:analysis* / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D006801:Humans; D008431:Maternal-Fetal Exchange / Q000276:immunology*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D010063:Ovum / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D011247:Pregnancy; D019836:Preimplantation Diagnosis / Q000295:instrumentation / Q000379:methods
D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I