<i>Extracellular vesicles deliver feto-placental paternal antigens to maternal secondary lymphoid tissues for T cell recognition.</i>

Abstract Pregnancy constitutes an immunological paradox, where despite the competent maternal immune system, semi-allogeneic fetus evades rejection. The mechanisms at maternal-fetal interface and mother’s secondary lymphoid tissues (SLTs) that dodge immunologic attack to fetus, remain largely unknown. Passage of extracellular vesicles (EVs) is a mechanism cell-to-cell communication transfer antigens (Ags), regulatory mediators, RNAs. Thus, we tested whether, similar transplantation, feto-placental EVs could transport fetoplacental Ags via blood SLT cells, in this case tolerogenic fashion Results: In female BALB/c mice impregnated with mOVA C57Bl/6 (B6) males, surrogate paternal Ag OVA accumulated on follicular dendritic cells (FDCs) SLTs (E17.5). mouse model which released by unit are labelled mNeonGreen linked EV-CD81, mNeonGreen-CD81 was detected microscopy punctate areas FDCs, conventional DCs, B macrophages spleen IP followed western blot from cultures trophoblast females B6 revealed EVs. Administration these non-pregnant induced defective activation proliferation OVA-specific T SLTs. human translational model, iv injection CM-DiI supernatant primary were captured macrophages, cDCs origin Conclusion: models tested, systemically carry paternal/trophoblast reach SLTs, recognized cells. NIH R01 AI148690.