One-carbon metabolism sustains effector T cell function through cell-surface glycosylation

Folate is a driver of one-carbon metabolism that is essential in T cells. The cellular consequences of its deprivation in CD8+ T cells and impact on anti-tumor function are unknown. Single cell RNA-seq analysis of primary central nervous system lymphoma (PCNSL) patients' tumor samples revealed exhaustion in T cells with high folate metabolism gene expression signature. Functional genomics, metabolite profiling, and glycomics identified disrupted cell surface glycosylation as a major consequence of folate deprivation in CD8+ T cells. Mechanistically, folate deprivation reduced nucleotide sugar levels, perturbed glycosylation, and triggered the apoptotic unfolded protein response. Overexpressing folate transporters in adoptively transferred CD8+ T cells increased intratumoral T cell numbers and reduced exhaustion. Therefore, our data draw a mechanistic line between one-carbon metabolism, cell-surface glycosylation, and anti-tumor T cell function, and support a hypothesis that increased folate uptake can enhance CD8+ T cell function including ex vivo and in vivo CAR-T cells.