What is the role of regulatory T cells in the success of implantation and early pregnancy?
OBJECTIVE
The immune system is well controlled by the balance between immunostimulation and immunoregulation. CD4(+)CD25(+) regulatory T (Treg) cells and an enzyme called indoleamine-2, 3-dioxygenase (IDO) mediate maternal tolerance of the allogeneic fetus. Treg cells, therefore, may prevent early pregnancy loss due to maternal 'rejection.'


METHODS
The latest understanding of tolerance during pregnancy is reviewed.


CONCLUSIONS
Recent data show that CD4(+)CD25(+) Treg cells play essential roles in the induction and maintenance of tolerance, and that they augment the IDO activity in dendritic cells and macrophages. Therefore, CD4(+)CD25(+) Treg cells and IDO enzyme may cooperate in the induction of tolerance during pregnancy. Treg deficiency is associated with very early post-implantation loss and spontaneous abortion in animal models, and low Treg levels are associated with recurrent miscarriages in humans.
Saito
Shigeru
S
Department of Obstetrics and Gynecology, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan. s30saito@med.u-toyama.ac.jp
Shima
Tomoko
T
Nakashima
Akitoshi
A
Shiozaki
Arihiro
A
Ito
Mika
M
Sasaki
Yasushi
Y
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism / Q000502:physiology; D010064:Embryo Implantation / Q000276:immunology*; D005260:Female; D006801:Humans; D007108:Immune Tolerance / Q000502:physiology; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D008285:Major Histocompatibility Complex / Q000235:genetics / Q000276:immunology; D008954:Models, Biological; D011247:Pregnancy; D011248:Pregnancy Complications / Q000276:immunology; D011261:Pregnancy Trimester, First / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000502:physiology*; D014327:Trophoblasts / Q000378:metabolism
D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D053645:Interleukin-2 Receptor alpha Subunit