title: Dynamic changes in fetal microchimerism in maternal peripheral blood mononuclear cells, CD4+ and CD8+ cells in normal pregnancy.
abstract: OBJECTIVE
  Cell trafficking during pregnancy results in persistence of small populations of fetal cells in the mother, known as fetal microchimerism (FMc). Changes in cell-free fetal DNA during gestation have been well described, however, less is known about dynamic changes in fetal immune cells in maternal blood. We have investigated FMc in maternal peripheral blood mononuclear cells (PBMC) longitudinally across gestation.
  
  
  METHODS
  Thirty-five women with normal pregnancies were studied. FMc was identified in PBMC, CD4+ and CD8+ subsets employing quantitative PCR assays targeting fetal-specific genetic polymorphisms. FMc quantities were reported as fetal genome equivalents (gEq) per 1,000,000 gEq mother's cells. Poisson regression modeled the rate of FMc detection.
  
  
  METHODS
  FMc in PBMC.
  
  
  RESULTS
  The probability of detecting one fetal cell equivalent increased 6.2-fold each trimester [Incidence Rate Ratio (IRR) 95% CI: 1.73, 21.91; p = 0.005]. Although FMc in PBMC was not detected for the majority of time points, 7 of 35 women had detectable FMc during pregnancy at one or more time points, with the majority of positive samples being from the third trimester. There was a suggestion of greater HLA-sharing in families where women had FMc in PBMC. FMc was detected in 9% of CD4+ (2/23) and 18% of CD8+ (3/25) subsets.
  
  
  CONCLUSIONS
  FMc in PBMC increased as gestation progressed and was found within CD4+ and CD8+ subsets in some women in the latter half of gestation. A number of factors could influence cellular FMc levels including sub-clinical fetal-maternal interface changes and events related to parturition. Whether FMc during pregnancy predicts persistent FMc and/or correlates with fetal-maternal HLA relationships also merits further study.
authors.affiliation: Division of Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98195-6460, USA. adamsk@u.washington.edu
authors.forename: K M
authors.initials: KM
authors.lastname: Adams Waldorf
authors.forename: H S
authors.initials: HS
authors.lastname: Gammill
authors.forename: J
authors.initials: J
authors.lastname: Lucas
authors.forename: T M
authors.initials: TM
authors.lastname: Aydelotte
authors.forename: W M
authors.initials: WM
authors.lastname: Leisenring
authors.forename: N C
authors.initials: NC
authors.lastname: Lambert
authors.forename: J L
authors.initials: JL
authors.lastname: Nelson
mesh_terms: D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D046528:Chimerism; D005260:Female; D005333:Fetus / Q000276:immunology*; D005865:Gestational Age; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D008431:Maternal-Fetal Exchange / Q000276:immunology; D011247:Pregnancy / Q000276:immunology*; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies
chemical_list: D006680:HLA Antigens