title: Regulatory T helper cells in pregnancy and their roles in systemic versus local immune tolerance.
abstract: OBJECTIVE
  During pregnancy, the maternal immune system needs to adapt in order not to reject the semi-allogenic fetus.
  
  
  METHODS
  In this review, we describe and discuss the role of regulatory T (Treg) cells in fetal tolerance.
  
  
  RESULTS
  Treg cells constitute a T helper lineage that is derived from thymus (natural Treg cells) or is induced in the periphery (induced Treg cells). Treg cells are enriched at the fetal-maternal interface, showing a suppressive phenotype. In contrast, Treg cells are not increased in the circulation of pregnant women, and the suppressive capacity is similar to that in non-pregnant women. However, aberrations in Treg frequencies and functions, both systemically and in the uterus, may be involved in the complications of pregnancy.
  
  
  CONCLUSIONS
  Treg cells seem to have distinguished roles locally versus systemically, based on their distribution and phenotype.
authors: Division of Clinical Immunology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden. jan.ernerudh@lio.se
authors: Jan
authors: J
authors: Ernerudh
authors: Göran
authors: G
authors: Berg
authors: Jenny
authors: J
authors: Mjösberg
mesh_terms: D000818:Animals; D005260:Female; D005333:Fetus / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D011247:Pregnancy / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*