Fig 1: Cardiolipin Is Necessary for In Vivo and In Vitro CD8+ T Cell Responses(A) Schematic of the cardiolipin synthesis pathway.(B) PTPMT1 expression in CD8+ T cells from PTPMT1 WT (Ptpmt1flox/floxCD4-Cre-/-) and PTPMT1-?T (Ptpmt1flox/floxCD4-Cre+/-) mice.(C) Cardiolipin content in freshly isolated Ptpmt1 WT and Ptpmt1-/- CD8+ T cells.(D) Percentage of CD8+ T cells in spleens from PTPMT1 WT and PTPMT1-?T mice. Dots represent individual mice.(E) PTPMT1 WT and PTPMT1-?T mice infected i.v. with 1 × 106 colony-forming units (CFU) LmOVA ?Acta and challenged i.v. with 5 × 107 CFU LmOVA 21 days after primary infection. Blood analyzed at indicated time.(F) Percentage of CD8+ T cells in PTPMT1 WT and PTPMT1-?T mice infected as in (E). Dots represent individual mice.(G) Percentage of CD8+ Tet+ T cells in PTPMT1 WT and PTPMT1-?T mice infected as in (E). Dots represent individual mice.(H) Bacterial burden shown as CFU per µg of liver of PTPMT1 WT and PTPMT1-?T mice 7 days post-LmOVA ?Acta challenge. Dots represent individual mice.(I) TN (CD62LhiCD44lo), TE (CD62LloCD44hi), and TM (CD62LhiCD44hi) CD8+ T cells from PTPMT1 WT and PTPMT1-?T mice 7 days after primary infection. Dots represent individual mice.(J) EEC, SLEC, MPEC, and DPEC CD8+ T cells from PTPMT1 WT and PTPMT1-?T mice 7 days after primary infection according to KLRG1 and CD127 expression. Dots represent individual mice.(K) OCR/ECAR ratio of WT and Ptpmt1-/- CD8+ T cells analyzed 7 days after secondary infection. Dots represent individual mice.(L) Ptpmt1 WT and Ptpmt1-/- CD8+ T cells stimulated with PMA/Iono for 4 h. Also shown is the percentage of CD8+ T cells producing IFN-? and IFN-? MFI of cytokine-producing cells.(M) Cytoplasmic calcium levels at baseline and after aCD3 crosslinking via IgG, tapsigargin (TG), and ionomycin (iono) in Ptpmt1 WT and Ptpmt1-/- CD8+ T cells. Representative of 3 experiments.(N) CD5, CD44, CD25, and CD69 expression in Ptpmt1 WT and Ptpmt1-/- CD8+ T cells 24 h after activation with aCD3/aCD28 + IL-2.(O) Survival of Ptpmt1 WT and Ptpmt1-/- CD8+ T cells 24 h after activation.(P) Cell cycle analysis assessed by FxCycle + Ki67 staining of Ptpmt1 WT and Ptpmt1-/- CD8+ T cells 24 h and 48 h after activation with aCD3/aCD28 + IL-2.(Q) Active proliferation assessed by Ki67 expression in Ptpmt1 WT and Ptpmt1-/- CD8+ T cells 24 h and 48 h after activation with aCD3/aCD28 + IL-2.(R) Cell proliferation assessed by CTV dilution of Ptpmt1 WT and Ptpmt1-/- CD8+ T cells 72 h after activation with aCD3/aCD28 + IL-2. Histogram representative of 4 independent experiments.Data shown as mean ± SEM of =3 independent experiments unless indicated. Statistical comparisons for 2 groups calculated by unpaired two-tailed Student’s t test, *p < 0.05; **p < 0.01; ***p < 0.001.See also Figure S2.