title: Measurements of CD56+ cells in peripheral blood and endometrium by flow cytometry and immunohistochemical staining in situ.
abstract: BACKGROUND
  CD56+ cells in peripheral blood or the endometrium may be increased in women with reproductive failure. However, the relationship between numbers of peripheral blood CD56+ and endometrial CD56+ cells is uncertain. The aim of this study was (i) to compare the numbers of CD56+ cells in peripheral blood and endometrium in samples taken simultaneously and (ii) to compare measurements by flow cytometry and immunohistochemistry of CD56+ cells in the same endometrial biopsy.
  
  
  METHODS
  Endometrial biopsies and blood were obtained from women with recurrent miscarriage (n= 25) on days LH+7-LH+9 of the cycle. The total number of CD56+, CD56+ CD16- and CD56+CD16+ cells in blood was measured by flow cytometry; the number of CD56+ cells in the endometrium was determined by immunohistochemistry. Endometrial samples were also obtained from fertile women (n= 20) and used to measure CD56+ and CD45+ cells, by both flow cytometry and immunostaining.
  
  
  RESULTS
  There was no correlation between the numbers of total CD56+, CD56+CD16- or CD56+CD16+ in peripheral blood and the number of endometrial CD56+ cells in the same women. In endometrium from fertile women, a significant correlation was found between the numbers of CD56+ cells measured by flow cytometry and immunohistochemistry (correlation= 0.497, P= 0.026, when expressed as % total cells; correlation= 0.570, P= 0.009 when expressed as % CD45+ cells).
  
  
  CONCLUSIONS
  Measurements of CD56+ cells in peripheral blood do not correlate with endometrial CD56+ cell numbers and therefore should not be extrapolated to events in the endometrium. In contrast, measurements of endometrial CD56+ cells by flow cytometry and immunostaining correlate well.
authors.affiliation: Biomedical Research Centre, Sheffield Hallam University, City Campus, Sheffield S1 1WB, UK. s.m.laird@shu.ac.uk
authors.forename: S M
authors.initials: SM
authors.lastname: Laird
authors.forename: N
authors.initials: N
authors.lastname: Mariee
authors.forename: L
authors.initials: L
authors.lastname: Wei
authors.forename: T C
authors.initials: TC
authors.lastname: Li
mesh_terms: D000026:Abortion, Habitual / Q000276:immunology; D019002:CD56 Antigen / Q000097:blood*; D004717:Endometrium / Q000166:cytology*; D005260:Female; D005434:Flow Cytometry; D058851:GPI-Linked Proteins / Q000097:blood; D006801:Humans; D007150:Immunohistochemistry; D007694:Killer Cells, Natural / Q000276:immunology*; D011247:Pregnancy; D017452:Receptors, IgG / Q000097:blood
chemical_list: D019002:CD56 Antigen; C428200:FCGR3B protein, human; D058851:GPI-Linked Proteins; D017452:Receptors, IgG