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International Journal of Reproductive Medicine
Volume 2013, Article ID 906813, 8 pages
Clinical Study

Natural Killer Cells and Their Activation Status in Normal Pregnancy

1Harris Birthright Research Centre for Fetal Medicine, King’s College Hospital, London SE5 9RS, UK
2Department of Obstetrics and Gynaecology, St. Helier Hospital, Carshalton SM5 1AA, UK
3Department of Obstetrics and Gynaecology, St. Mary’s Hospital, Imperial College Healthcare NHS Trust, London, UK
4Department of Immunology, St Helier Hospital, Carshalton, Surrey SM5 1AA, UK
5Department of Fetal Medicine, University College Hospital, London WC1E 6DB, UK

Received 9 December 2012; Revised 22 February 2013; Accepted 3 March 2013

Academic Editor: Yuping Wang

Copyright © 2013 Beatrice Mosimann et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Increased peripheral blood-activated NK cell counts are associated with increased risk of miscarriage and failed in vitro fertilization treatment. However, assessment of activated peripheral NK cells in normal and pathological pregnancies beyond implantation and early miscarriage has not been described. Total CD69 expressing NK cells counts were measured by flow cytometry in healthy women with singleton pregnancies, including 45 at 11+6–13+6 weeks’ gestation, 46 at 20+0–22+4 weeks, and 42 at 31+6–33+5 weeks. The number of peripheral blood NK cells decreased, whereas the percentage of activated CD69 expressing NK cells increased from the first to the third trimester of pregnancy. This study shows the course of peripheral blood NK cells and activated CD69 expressing NK cells in uncomplicated nulliparous singleton pregnancies. This is a first step in understanding their implication in pathological pregnancies.