title: Characterization of uterine NK cells in women with infertility or recurrent pregnancy loss and associated endometriosis.
abstract: OBJECTIVE
  Uterine natural killer cells (uNK) have been thought to play a key role in endometriosis and infertility. We investigated the expression of CD56, CD16, and NKp46 in endometrial tissues from 61 women with unexplained recurrent pregnancy loss (uRPL) or infertility (UI) and correlated this with the presence or absence of endometriosis. The results from the patients with subfertility were compared with those from 10 fertile patients.
  
  
  METHODS
  Mid-secretory phase endometrial biopsies were obtained, and the endometrial expression of CD56, CD16, or NKp46 was identified by immunohistochemistry and quantified (ImageJ Software).
  
  
  RESULTS
  The percentage of CD16(+) cells was higher in women with uRPL (7.9 ± 3.2) and UI (9.0 ± 5.5), even when these conditions were associated with endometriosis (8.9 ± 5.3), compared with fertile patients (5.6 ± 2.4, P < 0.05). Likewise, the ratio of NKp46(+) :CD56(+) cells was higher in women with uRPL (0.28 ± 0.25) and UI (0.21 ± 0.2), even when these conditions were associated with endometriosis (0.19 ± 0.14), compared with fertile patients (0.1 ± 0.1, P < 0.05). No differences were observed when comparing CD56.
  
  
  CONCLUSIONS
  Women, with or without endometriosis, who have larger populations of cytotoxic CD16(+) uNK cells and/or higher populations of NKp46(+) CD56(+) cells may be at greater risk of infertility disorders resulting from an inflammatory environment occurring during implantation or later during decidualization.
authors.affiliation: Department of Obstetrics, Gynecology and Reproductive Biology, College of Human Medicine, Michigan State University, Grand Rapids, MI, USA; Department of Obstetrics and Gynecology, Grand Rapids Medical Education Partners/Michigan State University, Grand Rapids, MI, USA.
authors.forename: Emma
authors.initials: E
authors.lastname: Giuliani
authors.forename: Kirstin L
authors.initials: KL
authors.lastname: Parkin
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Lessey
authors.forename: Steven L
authors.initials: SL
authors.lastname: Young
authors.forename: Asgerally T
authors.initials: AT
authors.lastname: Fazleabas
mesh_terms: D000026:Abortion, Habitual / Q000276:immunology*; D000328:Adult; D019002:CD56 Antigen / Q000276:immunology; D004715:Endometriosis / Q000276:immunology*; D005260:Female; D058851:GPI-Linked Proteins / Q000276:immunology; D006801:Humans; D007247:Infertility, Female / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D008875:Middle Aged; D055627:Natural Cytotoxicity Triggering Receptor 1 / Q000276:immunology; D017452:Receptors, IgG / Q000276:immunology; D014599:Uterus / Q000276:immunology*; D055815:Young Adult
chemical_list: D019002:CD56 Antigen; C428200:FCGR3B protein, human; D058851:GPI-Linked Proteins; C522918:NCAM1 protein, human; C112260:NCR1 protein, human; D055627:Natural Cytotoxicity Triggering Receptor 1; D017452:Receptors, IgG
keywords: Endometriosis; infertility; natural killer cells; recurrent pregnancy loss