Soluble human leukocyte antigen G in early human embryo cultures after assisted reproduction procedures

2Fertility Clinic, Vilnius, Lithuania Human leukocyte antigen G (HLA-G) is a non-classical HLA class I molecule which can be expressed in the membrane-bound or soluble form and is well known for its tolerogenic properties. Increasing interest is now being addressed to the soluble forms, because they might have prognostic properties in the implantation and pregnancy process. The aim of our study was to evaluate a correlation between embryo cleavage, morphology and soluble human leukocyte antigen G (sHLA-G) levels, to estimate the impact of sHLA-G concentration on pregnancy outcome. Materials and methods: The study was performed on a group of infertile patients with various infertility indications. In vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) procedure were used for insemination. After 72 h, on the day of transfer, the embryo morphology was evaluated, emryo transfer (ET) according to embryo morphology was performed, the supernatants of the transferred embryos were collected and stored at –90 °C. For the quantitative measurement of soluble forms of Human Leukocyte Antigen-G in cell culture supernatant we used the ELISA method. The ELISA kit from EXBIO Praha measures soluble HLA-G1 and HLA-G5 isoforms, plates are coated with mem-G9 MoAb and components are ready to use. The analysis of results was performed using the Statistics Package for Social Sciences SPSS 12.0. Results: A total of 16 couples participated in this study. In all, 145 embryo culture supernatants were tested for sHLA-G. Soluble form of human leukocyte antigen G was detected in 12 (9.0%) embryo culture samples (range, 0.4–20.5 IU/ml). The production of human leukocyte antigen did not depend on the morphological criteria of the embryo. No significant differences were found between sHLA-G concentration in patients from the IVF and ICSI groups. sHLA-G levels did not differ significantly in the embryo cleavage rate and pregnancy outcome. Conclusions: day 3 embryos secrete sHLA-G to the surrounding medium; the level of those soluble molecules can be detected using ELISA. The concentration of the human leukocyte antigen did not correlate with the number of blastomere and with the morphological criteria of the embryo. SHLA-G might be one of the markers of embryo implantation potential after IVF / ICSI procedures as a factor that helps to achieve and maintain pregnancy, but further investigations are required.