In Vitro Fertilized Embryos do not Secrete Detectable HLA-G on Day Two

Background: Pregnancy is a successful transplantation. The factors evading rejection of the fetus are poorly understood. Recently an interest has grown, in HLA-G molecules as one of these factors. Since these antigens are mainly expressed on the surface of cytotro-phoblasts that are in direct contact with maternal tissues, it has been suggested that these molecules may have a role in induction of immune tolerance in mothers. Objective: to find the association of soluble HLA-G (sHLA-G) and the success of pregnancy with intracyto-plasmic sperm injection (ICSI) procedure. Methods: In this study, the supernatant of 287 individually cultured embryos corresponding to 96 women under ICSI procedure were as-sayed for soluble HLA-G1 and G5 by a sandwich ELISA. Results: Clinical pregnancy suc-cessfully occurred in 30 of candidates. No differences in clinical parameters (age, infertility duration, stimulation regimen) were observed between pregnant and nonpregnant women under ICSI procedure. None of the embryo supernatants in either group showed any detect-able sHLA-G molecules. Conclusion: Our results showed that detectable level of sHLA-G is not produced by day 2 embryos and such a measurement may not provide reliable infor-mation for embryo selection and estimation of pregnancy success.