Early Pregnancy Human Decidua is Enriched with Activated, Fully Differentiated and Pro-Inflammatory Gamma/Delta T Cells with Diverse TCR Repertoires.

Pregnancy is a state where high and stage-dependent plasticity of the maternal immune system is necessary in order to equilibrate between immunosuppression of harmful responses towards the fetus and ability to fight infections. TCR cells have been implicated in the responses in infectious diseases, in the regulation of immune responses, and in tissue homeostasis and repair. The variety of functions makes T cells a particularly interesting population during pregnancy. In this study, we investigated the proportion, phenotype and TCR and repertoires of T cells at the maternal-fetal interface and in the blood of pregnant women using FACS, immunohistochemistry and spectratyping. We found an enrichment of activated and terminally differentiated pro-inflammatory T-cell effectors with specific location in the human decidua during early pregnancy, while no significant changes in their counterparts in the blood of pregnant women were observed. Our spectratyping data revealed polyclonal CDR3 repertoires of the 1, 2 and 3 chains and 2, 3, 4 and 5 chains and oligoclonal and highly restricted CDR39 repertoire of T cells in the decidua and blood of pregnant women. Early pregnancy induces recruitment of differentiated pro-inflammatory T-cell effectors with diverse TCR repertoires at the maternal-fetal interface.