Fig 1: Influence of CD73 on T cell survival and TRM differentiation in vivo(A) Cells isolated from spleen, lung, and jejunum tissues of three organ donors were analyzed for the expression of the TRM markers CD69 and CD103 within CD73+ and CD73-CD45RA- T cells. Representative contour plots on gated CD45+ cells (left panel for CD4 TMEM cells; right panel for CD8 TMEM cells) are shown. Subset distributions within CD73+ and CD73- CD45RA- CD4 and CD8 T cells are summarized as stacked bars. Error bars are included where data from more than one sample were available.(B) Mice were infected with Armstrong LCMV; CD73 expression on LCMV GP66–77 tetramer+ splenic CD4 T cells was determined on day 8 (effector stage) and day 85 (memory stage). Representative contour plots (left) and summary data from 3–6 mice (right). Data are compared by two-tailed unpaired t test. ***p < 0.001.(C) CD73 expression on tissue-resident LCMV GP61–80 tetramer+ CD4 T cells in lung and liver at day 66 after LCMV infection.(D) CD73 expression on virus-specific CD8 T cells (HLA-A2*02:01 tetramer with GILGFVFTL peptide from influenza M1 protein, left panel; HLA-A2*02:01 tetramer with GLCTLVAML peptide from lytic BMLF1 protein, right panel) from young, middle-age, and old adults. Top panels are representative scatterplots of tetramer staining and histograms of CD73 expression. Bottom panels are summary data of frequencies shown as boxplots. Frequencies in T cells from young and old adults were compared by unpaired t test and frequencies of CD73 expression on tetramer-positive and bulk T cells by paired t test. *p < 0.05, **p < 0.01. N.S., not significant.(E) CD4 T cells from WT mice (CD45.2+) or heterozygous mice (CD45.1+CD45.2+) were infected with retrovirus expressing CD73 shRNA or control shRNA. After sorting AmCyan+ cells (successfully transduced cells), congenic cells were mixed at 1:1 ratio before being transferred into WT mice through tail vein injection. After 1 day, mice were infected with Armstrong LCMV and sacrificed 20 days after infection. Transferred T cells from spleen, lung, and liver were analyzed for surface markers by flow cytometry. Contour plots are representative of two independent experiments.