Figure 3.

A schematic overview of CD8+ T cells at the feto-maternal interface. CD8+ T cells may migrate from blood (top, left), and whether they differentiate previously or subsequently to seeding in the decidual microenvironment remains unclear (dashed lines). Naive and memory CD8+ T cell populations have been detected in human decidua, whereas information about effector subsets is missing, indicated by a question mark. Among memory populations, TRM, EM, EMRA and CM were reported, and TPM or SCM subsets have not yet been studied. Particular features of decidual memory CD8+ T cells include unique cytokine secretion profile, elevated expression of inhibitory receptors, low basal cytotoxicity and the enrichment in clones specific for fetal antigens and viruses. Ligands for inhibitory receptors are expressed both in the decidua stroma (orange) and placenta (pink). EVT, extravillous trophoblasts.