Glucose is essential for T cell proliferation and function, yet its specific metabolic roles in vivo remain poorly defined. Here, we identify glycosphingolipid (GSL) biosynthesis as a key pathway fueled by glucose that enables CD8 + T cell expansion and cytotoxic function in vivo . Using 13 C-based stable isotope tracing, we demonstrate that CD8 + effector T cells use glucose to synthesize uridine diphosphate-glucose (UDP-Glc), a precursor for glycogen, glycan, and GSL biosynthesis. Inhibiting GSL production—by targeting the enzymes UDP-Glc pyrophosphorylase 2 (UGP2) or UDP-Glc ceramide glucosyltransferase (UGCG)—impairs CD8 + T cell expansion and cytolytic activity without affecting glucose-dependent energy production. Mechanistically, we show that glucose-dependent GSL biosynthesis is required for plasma membrane lipid raft integrity and aggregation following TCR stimulation. Moreover, UGCG-deficient CD8 + T cells display reduced granzyme expression and tumor control in vivo . Together, our data establish GSL biosynthesis as a critical metabolic fate of glucose—independent of energy production—required for CD8 + T cell responses in vivo .

Glucose-dependent glycosphingolipid biosynthesis fuels CD8+T cell function and tumor control