title: Suppression of natural killer cell activity by monocytes following immunotherapy for recurrent spontaneous aborters.
abstract: OBJECTIVE
  Natural killer (NK) cell activity has previously been shown to decrease in normal pregnancy as compared with the nonpregnancy state. The purpose of this study was to determine NK cell activity in recurrent aborters and to investigate the kinetics of NK cell activity following immunotherapy.
  
  
  METHODS
  Recurrent aborters (N = 17) were immunized with husbands' mononuclear cells (1 x 10(8)) twice during the early stage of current pregnancy. NK cell activity of recurrent aborters as well as that of normal pregnant (N = 12) and nonpregnant (N = 6) women (controls) was determined by 51Cr release assay. Monocytes were depleted from the mononuclear cell fraction and its effect on the NK cell activity was determined as well.
  
  
  RESULTS
  At around 5 wk of gestation, NK cell activity in recurrent aborters before treatment was significantly higher (28.0 +/- 5.1%) than that in normal pregnancy (18.9 +/- 4.3%) (P < 0.01). Following immunotherapy, NK cell activity of recurrent aborters (N = 13) who maintained their pregnancy decreased significantly (21.7 +/- 8.9%) (P < 0.05). In contrast, NK cell activity of recurrent aborters (N = 4) who aborted their current pregnancy did not decrease. Depletion of monocytes resulted in a significant increase in NK cell activity (P < 0.05).
  
  
  CONCLUSIONS
  This study suggests that the immunotherapy induces suppression of NK cell activity which may contribute for the maintenance of pregnancy. Moreover, monocytes may be involved in this suppression.
authors.affiliation: Department of Molecular Biology, Nagoya City University Medical School, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Higuchi
authors.forename: K
authors.initials: K
authors.lastname: Aoki
authors.forename: T
authors.initials: T
authors.lastname: Kimbara
authors.forename: N
authors.initials: N
authors.lastname: Hosoi
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Okada
mesh_terms: D000026:Abortion, Habitual / Q000276:immunology* / Q000628:therapy; D000328:Adult; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic; D005260:Female; D006801:Humans; D007108:Immune Tolerance; D007167:Immunotherapy; D007694:Killer Cells, Natural / Q000276:immunology*; D009000:Monocytes / Q000276:immunology*; D011247:Pregnancy