ON THE ISSUE OF STANDARDIZATION OF UTERINE NATURAL KILLER CELL MEASUREMENT IN PATIENTS WITH RECURRENT PREGNANCY LOSS.

Disturbed endometrial factor, as a result of disbalance of immune cells, is regarded as one of the most controversial immunological pathways of RPL. Uterine NK (uNK) cells are major immune cells present in endometrium and key players in tolerogenic immune mechanisms during implantation/placentation in the first trimester of pregnancy. There is a growing interest worldwide in understanding the potential role of altered number and function of uNK cells towards the reproductive outcome. Intensive research is being carried out to find out reliable immune markers to predict the potential risk for subsequent miscarriage. Therefore, the measurement of uNK cells acquires more significance in research settings and in clinical investigational protocols as well. Furthermore, there is an increasing demand from couples with RPL for an "uNK cell count test" and "immune treatments". Methods of measurement of uNK cells during the last decades have been challenged with many factors, that have produced various types of investigational errors and differences in results between the research centres. Researchers emphasize an urgent need for an agreed standardized protocol for the measurement of uNK cells, in order to minimize variations between the results of different centres and translate NK cell research into clinical practice. The aim of this article is to highlight the methods of uNK cell measurement in women with RPL during the last decade, to analyse our own difficulties during the endometrial tissue sampling/processing, to describe a reliable methodology of uNK cell investigation by immunohistochemical approach and summarize current trends in this direction to the establishment of the standardized protocol.