Purine nucleobases enhance CD8+ T cell effector function

During antiviral immune responses, activated immune cells remodel metabolic pathways towards uptake and utilization of biosynthetic and bioenergetic metabolites. Concurrently, viral infections alter metabolic environments, impacting metabolite availability for the establishment of an effective immune response. Here, we integrated in vivo metabolomics data from murine and human viral infections with in vitro metabolite screens, identifying purine nucleobases as novel immunometabolites that enhance CD8+ T cell effector function. We found that CD8+ T cells can switch from resource-intensive purine de novo synthesis to purine salvage pathway, to produce nucleotides from purine nucleobases. This strategy of metabolic adaptation allows diversion of biosynthetic and bioenergetic resources towards enhancing effector molecule production. Our findings unveil an adaptation strategy by CD8+ T cells to manage metabolic challenges in dynamic organismal environments and suggest pharmacological targets in purine metabolism as potential targets for immunotherapy.