The Role of Regulatory T Cells in Materno-Fetal Tolerance

Abstract

Maternal immune tolerance to paternal allo-antigens expressed by the fetus is a precondition of successful pregnancy in viviparous mammals. This occurs despite exposure of the maternal immune system to potentially immunogenic fetal tissue. Local immune evasion mechanisms are thought to prevent maternal immune aggression towards the fetus. Nevertheless, maternal lymphocytes capable of mediating anti-fetal immune aggression are detectable throughout gestation. This review focuses on the role played by regulatory T cells in suppressing alloreactive immune responses, thereby promoting materno-fetal tolerance. The characteristics of naturally occurring regulatory T cells, their function in mouse and human pregnancy and the implications for infertility, premature abortion syndromes, transplantation and autoimmunity are discussed in detail.