To obtain a full understanding of functional epitopes recognized by CD8+ T cells, Kula et al. developed and validated T-Scan, a high-throughput, physiologically relevant cell-based screening platform for epitope discovery and TCR analysis. T-Scan was effectively applied to discovery of pathogen epitopes, detailed mapping of the HLA:peptide:TCR interface, and human genome-wide screening and discovery of self-reactive tumor TCR specificity. In cancer immunotherapy, T-Scan applications include identifying novel targets in patient TILs, discovering the targets of orphan TCRs, and revealing potential off-target reactivities of therapeutic TCRs.
Contributed by Katherine Turner
T cell recognition of specific antigens mediates protection from pathogens and controls neoplasias, but can also cause autoimmunity. Our knowledge of T cell antigens and their implications for human health is limited by the technical limitations of T cell profiling technologies. Here, we present T-Scan, a high-throughput platform for identification of antigens productively recognized by T cells. T-Scan uses lentiviral delivery of antigen libraries into cells for endogenous processing and presentation on major histocompatibility complex (MHC) molecules. Target cells functionally recognized by T cells are isolated using a reporter for granzyme B activity, and the antigens mediating recognition are identified by next-generation sequencing. We show T-Scan correctly identifies cognate antigens of T cell receptors (TCRs) from viral and human genome-wide libraries. We apply T-Scan to discover new viral antigens, perform high-resolution mapping of TCR specificity, and characterize the reactivity of a tumor-derived TCR. T-Scan is a powerful approach for studying T cell responses.