Detecting Tumor Antigen-Specific T Cells via Interaction-Dependent Fucosyl-Biotinylation

Abstract

Re-activation and clonal expansion of tumor-specific antigen (TSA)-reactive Tcells are critical to the success of checkpoint blockade and adoptive transfer of tumor-infiltrating lymphocyte (TIL)-based therapies. There are no reliable markers to specifically identify the repertoire of TSA-reactive Tcells due to their heterogeneous composition. We introduce FucoID as a general platform to detect endogenous antigen-specific Tcells for studying their biology. Through this interaction-dependent labeling approach, intratumoral TSA-reactive CD4+, CD8+ Tcells, and TSA-suppressive CD4+ Tcells can be detected and separated from bystander Tcells based on their cell-surface enzymatic fucosyl-biotinylation. Compared to bystander TILs, TSA-reactive TILs possess a distinct Tcell receptor (TCR) repertoire and unique gene features. Although exhibiting a dysfunctional phenotype, TSA-reactive CD8+ TILs possess substantial capabilities of proliferation and tumor-specific killing. Featuring genetic manipulation-free procedures and a quick turnover cycle, FucoID should have the potential of accelerating the pace of personalized cancer treatment.