title: Preconception peripheral natural killer cell activity as a predictor of pregnancy outcome in patients with unexplained infertility.
abstract: OBJECTIVE
  Preconception high peripheral natural killer (NK) cell activity in women with recurrent spontaneous abortion can predict subsequent miscarriages. We have examined prospectively, for the first time, the pregnancy rate in patients with unexplained infertility by measuring the peripheral NK activity.
  
  
  METHODS
  We tested the peripheral NK activity of 94 infertile women who despite treatment were unable to conceive for 6 or more months (mean; 2.4 years). Peripheral NK activity was measured by a chromium-51 release cytotoxicity assay. Women were followed for 2 years and assessed.
  
  
  RESULTS
  In 77 patients who were followed for 2 years, 28 had conceived but 49 did not. The peripheral NK activity of the group that became pregnant (mean +/- S.D.; 34.5 +/- 13.8%) was significantly lower than that of non-conception group (42.3 +/- 13.3%, P = 0.017).
  
  
  CONCLUSIONS
  Our finding suggests that elevated peripheral NK activity in patients with unexplained infertility is a risk factor for attaining pregnancy success.
authors.affiliation: Department of Obstetrics and Gynecology, Tokai University School of Medicine, Kanagawa, Japan. hide-m@is.icc.u-tokai.ac.jp
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Matsubayashi
authors.forename: Masako
authors.initials: M
authors.lastname: Shida
authors.forename: Akane
authors.initials: A
authors.lastname: Kondo
authors.forename: Takahiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Sugi
authors.forename: Shun-Ichiro
authors.initials: S
authors.lastname: Izumi
authors.forename: Takashi
authors.initials: T
authors.lastname: Hosaka
authors.forename: Tsunehisa
authors.initials: T
authors.lastname: Makino
mesh_terms: D000026:Abortion, Habitual / Q000378:metabolism; D000328:Adult; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000175:diagnosis*; D007694:Killer Cells, Natural / Q000378:metabolism*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011379:Prognosis