Extended Data Fig. 6 | Cd4-driven Cre recombinase expression efficiently deletes CD39 on CD8 + TIL. (a, b) TIL analysis of CD39 and inhibitory expression in CD8 + T cells from Cd4 Cre Entpd1 f/f mice. (c) Cell counts per milligram of tumor mass from experiments in Extended Data Fig. 6a, b. (d) Tumor areas at day 14 from experiments in Fig. 2f. (e) Suppression assay of Cd4 Cre Entpd1 f/f Thy1.1 + CD44 + OT-I T eff cells isolated from day 8 of acute Vaccinia OVA infection. (f) CD39 expression on TIL tT ex cells or Vaccinia OVA OT-I T cells in suppression assay co-cultures. (g) Suppression assay of B16-F10-derived CD8 + tT ex cells co-cultured with OT-I TCR transgenic CD8 + T cells. Culture were stimulated with either anti-CD3 antibodies as before, or OT-I specific peptide, SIIFEKL. (h-j) Flow cytometric analysis of TIL following suppression assay from Extended Data Fig. 6g. Statistics are Mann-Whitney (B-D,H-J) and linear regression (E,G) with * p < 0.05, * * p < 0.01,

Iron has long been established as a critical mediator of T cell development and proliferation. However, the mechanisms by which iron controls CD4 T cell activation and expansion remain poorly understood. In this study, we show that stimulation of CD4 T cells from C57BL/6 mice not only decreases total and labile iron levels but also leads to changes in the expression of iron homeostatic machinery. Additionally, restraining iron availability in vitro severely inhibited CD4 T cell proliferation and cell cycle progression. Although modulating cellular iron levels increased IL-2 production by activated T lymphocytes, CD25 expression and pSTAT5 levels were decreased, indicating that iron is necessary for IL-2R–mediated signaling. We also found that iron deprivation during T cell stimulation negatively impacts mitochondrial function, which can be reversed by iron supplementation. In all, we show that iron contributes to activation-induced T cell expansion by positively regulating IL-2R signaling and mitochondrial function.

No abstract