Establishing Maternal Tolerance: The Role of Regulatory T Cells (Tregs) in Pregnancy and Pathophysiology of Preeclampsia

Embryonic implantation is the result of a highly coordinated immunological shift resulting in a very localized, uterine specific, immune suppression of activated maternal response to fetal alloantigens. Without this coordinated immunological shift the result would be fetal demise and termination of genetic propagation. Hence, maternal immunological acceptance of the fetal allograft is imperative for the survival of any species that participates in allogeneic mating. While these events have occurred since the beginning of our species, the mechanisms and key factors that regulate this immunological shift are still not well understood and continue to astonish immunologists and reproductive physiologists. While we have not yet discovered all pathways utilized by our immune system to promote fetal tolerance, we are very aware of the development of obstetrical complications that arise from improper maternal immune tolerance. This review highlights key investigations that have focused on the discovery and role of regulatory T cells (Tregs) in the pathophysiology of preeclampsia and how these cells impact the immune dynamics at the maternal fetal interface.