Uterine natural killer (uNK) cells form the major leucocyte population in the endometrium at the time of implantation and have received considerable attention in relation to their role in normal implantation and early placental development. Particular interest has been paid to their potential role in pregnancy pathology; specifically the role of uNK cells in recurrent miscarriage (RM) and recurrent implantation failure (RIF). Although several clinical studies have suggested that peripheral blood (PB) natural killer (NK) cells and/or uNK cells are increased in women with RM and RIF, data to date is inconclusive because of significant heterogeneity across studies arising from the use of different methods to quantify NK cells. An understanding of the role of these cells in reproductive failure and their value in clinical practice will not be established until a consensus is reached on how they should be measured.
In this Scientific Impact Paper, the data relating to NK cell function will be reviewed and recommendations made regarding the measurement of NK cells in women with reproductive failure.
This Scientific Impact Paper was developed prior to the emergence of the COVID-19 coronavirus.
This is the first edition of this paper. Please note that the Scientific Advisory Committee regularly assesses the need to update. Further information on this review is available on request.
Developer declaration of interests
Professor SM Laird, Sheffield Hallam University, Sheffield: None declared.
Dr GE Lash, Guangzhou Women and Children’s Medical Center, China, and the Institute of Cellular Medicine, Newcastle University: Dr Lash has received honorarium from Elsevier for her work as Editor of ‘Trophoblast Research’ (the annual supplement to ‘Placenta’).
Professor TC Li FRCOG, Hong Kong: None declared.
Dr JN Bulmer, Royal Victoria Infirmary, Newcastle upon Tyne: None declared.