Immunologically active cells and infertility ‐ Quantification of uterine Natural Killer cells in endometrial samples from patients with recurrent implantation failure

Abstract

BackgroundDespite enormous advancements of reproductive medicine, recurrent implantation failure and habitual abortion remain an ongoing issue. One of the most important aspects of successful implantation is the intricate immune regulation necessary for the acceptance of the hemiallogenic embryo. The most numerous immune cells in the decidua are uterine Natural Killer (uNK) cells. Studies suggest that changes in the uNK cells count and physiology may be responsible for the aforementioned conditions. Thus, the uNK cells testing may provide valuable insights into their pathogenesis.MethodsWe compared Pipelle endometrial sampling with conventional curettage to find out whether the less invasive Pipelle method is a viable alternative of tissue collection.ResultsWe examined tissue samples from 9 patients obtained by both methods. The average size of tissue samples obtained with pipelle was 10,27 mm2, samples obtained with curettage had on average 18,74 mm2. Using immunohistochemical visualization of CD56 (NK cells) and granzyme B antigens (serine protease‐expressing activation state of NK cells), we found out that the average total count of CD56 / mm2 was for pipelle 90,13 and 84,04 for curettage. We also proved a correlation between granzyme B positivity and identification of NK cells clusters. The results showed that Pipelle endometrial sampling is a suitable method of tissue harvesting for the purpose of uNK cells examination. Discussion: Pipelle endometrial sampling is safe, cost‐effective and can be performed on an outpatient basis without the need of anaesthesia or analgesia. Several issues remain to be solved: how to standardize the subsequent uNK cells testing, how to interpret the results and finally yet importantly, how to use this knowledge in personalized treatment protocols.