ResultsCD8+ EM dT Have a Mixed Gene

ResultsCD8+ EM dT Have a Mixed Gene-Expression Profile.A significantly increased percentage of CCR7−CD45RA− EM CD8+ T cells and a decrease in CCR7+CD45RA+ naïve CD8+ T cells was observed in first trimester (6–12 wk) and term (>37 wk) pregnancy decidual tissue when compared with peripheral blood CD8+ T cells (CD8+ pT), confirming previous studies (Fig. S1 A–D) (22, 34). Within the EM subsets, TEM1 cells, defined as CD28+CD27+ EM cells, were significantly increased in the first trimester compared with term pregnancy decidua (Fig. S1E). Furthermore, a small but not significant increase in CD28−CD27+ TEM2 and CD28−CD27− TEM3 cells was detected in term compared with first trimester pregnancy decidua. Analysis of the cytolytic molecule PRF also showed reduced expression in first trimester decidual CD8+ effector (Eff) and TEM3 cells compared with the same populations in blood, as has previously been described for term CD8+ dT (Fig. S1F) (22). Gene-expression profiles were generated from RNA purified from CD8+CCR7−CD45RA− EM T cells in blood (CD8+ EM pT) and decidua (CD8+ EM dT; 6–12 wk and >37 wk). Unsupervised principle component analysis (PCA) separated CD8+ EM dT from CD8+ EM pT along the first principal component (35.9% of variance). PC2 separated first trimester from term pregnancy CD8+ EM dT (18.0% of variance) (Fig. 1A). A transcriptional signature that uniquely defined CD8+ EM dT and EM pT was identified (Fig. S2A and Dataset S1). Genes up-regulated in CD8+ EM dT compared with EM pT included genes involved in chemotaxis (CCL3, CCL4, IL-8, XCL1), T cell activation (IFN-γ, TNF, FOS, ICOS, NFKB1), and coinhibitory receptors (FASLG, CTLA4, LAG3, TIGIT, CRTAM, and TIM3). An increase in mRNA for granzymes, but not the other cytolytic molecules PRF and granulysin, was observed in term CD8+ EM dT (Fig. S3A).