Endometrial NK Cell Subpopulations CD16 ?￠???? CD56 Bright and CD16 ?￠???? CD56 Dim in Women with Recurrent Implantation Failure

摘要

Uterine NK (uNK) cells constitute the greatest proportion of maternal decidual leukocytes during pregnancy, which suggest that they have an important role in endometrial receptivity and embryo implantation. Identifying specific biomarkers for successful uterine receptivity and decreased risk of implantation failure would improve the tools of the assisted reproductive technology. Usually, CD56 dim uNK cells are negatively associated with the assisted reproductive outcome, whereas the CD56 bright CD16 ?￠???? uNK cells are associated with successful implantation and decidualization. In this study, we evaluated the distribution of NK subpopulations in women with recurrent implantation failure (RIF). Blood samples and endometrial biopsies from a total of 113 women with RIF attending our clinic for in vitro fertilization (IVF) treatment were analyzed. Our results showed elevated levels (>12%) of double positive (CD56 + CD16 + ) peripheral blood NK cells in 24 women, and 57 women with double positive peripheral blood NK cells (<12%). The proportions of total uNK cells in the peri-implantation endometrium of these women were similar in both groups. In addition, the proportion of CD16 ?￠???? CD56 dim uNK cells was significantly higher in women with unexplained infertility than in women with previously experienced ectopic, or extrauterine, pregnancy. Therefore, the imbalance between CD16 ?￠???? CD56 dim and CD16 ?￠???? CD56 bright uNK cells may have important functional implications in women with RIF and could be used as a diagnostic marker associated with endometrial quality.