Metabolic Profiling Using Stable Isotope Tracing Reveals Distinct Patterns of Glucose Utilization by Physiologically...

Naive CD8⁺ T cells differentiating into effector T cells increase glucose uptake and shift from quiescent to anabolic metabolism. Although much is known about the metabolism of cultured T cells, how T cells use nutrients during immune responses in vivo is less well defined. Here, we combined bioenergetic profiling and ¹³C-glucose infusion techniques to investigate the metabolism of CD8⁺ T cells responding to Listeria infection. In contrast to in vitro-activated T cells, which display hallmarks of Warburg metabolism, physiologically activated CD8⁺ T cells displayed greater rates of oxidative metabolism, higher bioenergetic capacity, differential use of pyruvate, and prominent flow of ¹³C-glucose carbon to anabolic pathways, including nucleotide and serine biosynthesis. Glucose-dependent serine biosynthesis mediated by the enzyme Phgdh was essential for CD8⁺ T cell expansion in vivo. Our data highlight fundamental differences in glucose use by pathogen-specific T cells in vivo, illustrating the impact of environment on T cell metabolic phenotypes.