Evidence that CD8 T-cell homeostasis and function remain intact during murine pregnancy.

Evolving models of immune tolerance have challenged the view that the response of the maternal immune system to environmental or fetal antigens must be suppressed or deviated. CD8 T cells play a central role in the immune response to viruses and intracellular pathogens so the maintenance of both the number and function of these cells is critical to protect both the mother and fetus. We show that the numbers of maternal CD8 T cells in both the spleen and the uterine draining lymph nodes are transiently increased at mid-gestation and this correlates with enhanced CD8 T-cell proliferation and an increased relative expression of both pro-survival and pro-apoptotic molecules. In transgenic mice bearing T-cell antigen receptors specific for the male HY or allo-antigens, the transgenic CD8 T cells retain the ability to proliferate and function during pregnancy. Moreover, anti-HY T-cell receptor transgenic mice have normal numbers of male pups despite the presence of CD8 T cells at the maternal-fetal interface. These data suggest that pregnancy is a dynamic state in which CD8 T-cell turnover is increased while the function and ending size of the CD8 T-cell compartment are maintained.