Fig. 3: Amino acid supply controls autophagy in CD8 T cells.

a, Kynurenine (KYN; System L substrate) uptake of antigen-activated CD8 T cells maintained in IL-2, IL-4, IL-21 and IL-15. b, Flow cytometry profiles of autophagy flux and kynurenine uptake of antigen-activated CD8 T cells maintained in indicated cytokines for 24 h. c, Protein copies per cell of SLC7A5, SLC1A5 and SLC7A1 in CTLs and antigen-activated OT-1 CD8 T cells. d, GFP/mCherry fluorescence of 24 h CD3/CD28-activated mCherry–GFP–LC3b CD8 T cells. Left panel, high and repressed autophagy flux is indicated; center panel, kynurenine uptake in IL-7 maintained, or high vs repressed autophagy of CD3/CD28-activated CD8 cells; right panel, kynurenine uptake in presence or absence of BCH (System L competitive substrate). e, Left panel, GFP/mCherry fluorescence of mCherry–GFP–LC3b CD8 T cells from day 3 LmOVA-infected mice; high and repressed autophagy populations indicated. Center and right panels, kynurenine uptake of high and repressed autophagy populations. UIC, uninfected control. f, Autophagy flux and kynurenine uptake of CD44⁺ mCherry–GFP–LC3b CD8 T cells from day 3 LmOVA-infected mice. g, Kynurenine uptake of CD44⁺ and CD44⁻ mCherry–GFP–LC3b CD8 T cells from day 7 LmOVA-infected or control mice. h, Autophagy flux and KYN uptake of CD44⁺ mCherry–GFP–LC3b CD8 T cells from day 7 LmOVA-infected mice. i, Autophagy flux of IL-7 maintained or 24 h CD3/CD28-activated mCherry–GFP–LC3b CD8 T cells cultured in RPMI or HBSS. j, Autophagy flux of mCherry–GFP–LC3b CD8 T cells ex vivo or 24 h CD3/CD28-activated in RPMI/HBSS/RPMI lacking methionine (no Met), arginine (no Arg) or glutamine (no Gln). k, Left panel, GFP/mCherry fluorescence of mCherry–GFP–LC3b CTLs maintained in RPMI, or switched into HBSS ± 200 nM BAF for 24 h. Right panel, autophagy flux over experimental time course. l, Left panel, autophagy flux in mCherry–GFP–LC3b CTLs maintained in RPMI, switched into HBSS or RPMI lacking methionine, arginine or glutamine for 24 h. Right panel, autophagy flux time course for these conditions. m, Left panel, autophagy flux of mCherry–GFP–LC3b CTLs maintained in RPMI or HBSS (no amino acids (no AA)) for 12 h, and HBSS for 12 h followed by RPMI for 10 h. Right panel, autophagy flux in CTLs maintained in RPMI or HBSS for 12 h, followed by RPMI for 6 h, 8 h and 10 h. Proteomic data in c are from ref. ²². Data are from n = 5–6 (a,b), n = 3 (c,i–m), n = 4 (d), n = 3–9 (e–h) and n = 5–6 (a,b) mice or biological replicates per condition. Flow plots show representative data. Bar charts and violin plot data indicate biological replicates. Error bars, s.d. Data in k and l were analyzed using two-way ANOVA with Fisher’s least significant difference test.