Marilen Benner

CHAPTER 4 84 ABSTRACT Well-timed interaction of correctly functioning maternal immune cells is essential to facilitate healthy placenta formation, as the uterine immune environment has to tolerate the semi- allogeneic fetus, and allow adequate trophoblast invasion. Here, we assess the uterine immune signature before and during pregnancy. Extensive supervised and unsupervised flow cytometry clustering strategies not only show a general increase in immune memory throughout pregnancy, but also reveal a continuous presence of B cells. Contrary to the belief that B cells are merely a consequence of uterine pathology, decidual B cells produce IL-10 and are found to be localized in clusters, together with Foxp3 + T cells. Our findings therefore suggest a role for B cells in healthy pregnancy.