title: Effect of pregnancy on thymic T cell development.
abstract: OBJECTIVE
  The thymus gland decreases in size during pregnancy. The significance of this alteration is not known.
  
  
  METHODS
  In this report, we examined thymic function by evaluating the development of T lymphocytes in the thymus of pregnant Balb/c mice at 15 and 20 days gestation using multi-color flow cytometry. Comparative analysis was made with non-pregnant mice, post-partum lactating mice, and postpartum non-lactating mice.
  
  
  RESULTS
  Progressive reduction of thymic size and cellularity during pregnancy was observed. All of the CD4 and CD8 defined subsets were reduced, with a disproportionate loss of CD4+, CD8+ double positive cells. Examination of the CD4-, CD8- double negative compartment revealed a predominance of TCR alpha, beta+ double negative cells, and a striking loss of precursor cells. The CD3-, CD4-, CD8- triple negative thymic subset was composed almost entirely of the earliest population (CD44+, CD25-), with the remaining maturational stages (CD44+, CD25+; CD44-, CD25+; and CD44-, CD25-) depleted. At 2 weeks postpartum, the subset ratios normalized, and the total cell count showed recovery.
  
  
  CONCLUSIONS
  T cell development is blocked at the precursor level during the mouse pregnancy. These effects are transient, and gradual recovery is observed in the postpartum period.
authors.affiliation: Department of Obstetrics and Gynecology, University of Iowa College of Medicine, Iowa City 52242-1080, USA.
authors.forename: A G
authors.initials: AG
authors.lastname: Rijhsinghani
authors.forename: S K
authors.initials: SK
authors.lastname: Bhatia
authors.forename: L T
authors.initials: LT
authors.lastname: Tygrett
authors.forename: T J
authors.initials: TJ
authors.lastname: Waldschmidt
mesh_terms: D000818:Animals; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology; D002454:Cell Differentiation / Q000276:immunology; D005260:Female; D018655:Lymphocyte Count; D051379:Mice; D008807:Mice, Inbred BALB C; D049590:Postpartum Period / Q000276:immunology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000276:immunology*; D013234:Stem Cells / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology* / Q000502:physiology*