Changes in Endometrial Natural Killer Cell Expression of CD94, CD158a and CD158b Are Associated With Infertility

Am J Reprod Immunol. 2009 Apr;61(4):265-76. doi: 10.1111/j.1600-0897.2009.00688.x.


Problem: Cycle-dependent fluctuations in natural killer (NK) cell populations in endometrium and circulation may differ, contributing to unexplained infertility.

Method of study: NK cell phenotypes were determined by flow cytometry in endometrial biopsies and matched blood samples.

Results: While circulating and endometrial T cell populations remained constant throughout the menstrual cycle in fertile and infertile women, circulating NK cells in infertile women increased during the secretory phase. However, increased expression of CD94, CD158b (secretory phase), and CD158a (proliferative phase) by endometrial NK cells from infertile women was observed. These changes were not reflected in the circulation.

Conclusion: In infertile women, changes in circulating NK cell percentages are found exclusively during the secretory phase and not in endometrium; cycle-related changes in NK receptor expression are observed only in infertile endometrium. While having exciting implications for understanding NK cell function in fertility, our data emphasize the difficulty in attaching diagnostic or prognostic significance to NK cell analyses in individual patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • CD3 Complex
  • CD56 Antigen
  • Cell Count
  • Cell Separation
  • Chronobiology Phenomena / immunology
  • Endometrium / immunology
  • Endometrium / pathology
  • Female
  • Flow Cytometry
  • Follicular Phase / blood
  • Follicular Phase / immunology
  • Humans
  • Infertility, Female / blood
  • Infertility, Female / immunology*
  • Killer Cells, Natural / immunology
  • Killer Cells, Natural / metabolism*
  • Killer Cells, Natural / pathology
  • Luteal Phase / blood
  • Luteal Phase / immunology
  • NK Cell Lectin-Like Receptor Subfamily D / genetics
  • NK Cell Lectin-Like Receptor Subfamily D / immunology
  • NK Cell Lectin-Like Receptor Subfamily D / metabolism*
  • Receptors, KIR2DL1 / genetics
  • Receptors, KIR2DL1 / immunology
  • Receptors, KIR2DL1 / metabolism*
  • Receptors, KIR2DL3 / genetics
  • Receptors, KIR2DL3 / immunology
  • Receptors, KIR2DL3 / metabolism*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism
  • T-Lymphocytes / pathology


  • CD3 Complex
  • CD56 Antigen
  • NK Cell Lectin-Like Receptor Subfamily D
  • Receptors, KIR2DL1
  • Receptors, KIR2DL3