DGAT1 mediates sex-specific CD8⁺ T cell antitumour responses

Fatty acid (FA) oxidation plays an important role in T cell responses. However, whether DGAT1-mediated FA esterification to triacylglycerol also regulates T cell function remains unclear. Here we uncover a sexually dimorphic requirement for DGAT1 expression in CD8⁺ tumour-infiltrating lymphocyte function. In female mice, T cell-specific Dgat1 deficiency improves mitochondrial metabolic fitness and expands the pool of progenitor exhausted CD8⁺ T (T_ex) cells to sustain antitumour responses. In male mice, however, Dgat1 deficiency leads to FA peroxidation, endoplasmic reticulum (ER) stress and CD8⁺ T_ex cell death. We show that these effects are mediated by androgen receptor (AR) signalling. Deletion of Ar, overexpression of glutathione peroxidase 4, or inhibition of ER stress-induced cell death rescues Dgat1-deficient CD8⁺ T cell survival and promotes antitumour responses in male mice. Overall, this study suggests that DGAT1 detoxifies AR signalling in male mice to protect against ER stress-induced cell death and maintain T cell stemness, and uncovers sex-specific metabolic adaptations in the tumour microenvironment.