Seminars

T cells play an important role in adaptive immunity by using their T cell receptors (TCRs) to recognize and eliminate target cells displaying peptide-MHCs (pMHCs). However, studying TCR-pMHC interactions remains a challenge due to the interface’s combinatorial diversity and a lack of high-throughput tools to build antigen libraries. Here, we engineer pMHC-pseudotyped lentiviruses in pool to assemble large antigen libraries that can activate and infect target T cells, enabling identification of TCR-pMHC pairs to inform immunotherapies.

Although most TCRs bind pMHC in a diagonal orientation, many complexes deviate from this “canonical” geometry, with lateral shifts, changes in crossing angle, and tilted orientations over the pMHC surface. Even within canonical docking, contacts vary across TCRs, even those reactive to identical antigens, creating distinct “footprints”. These footprints are thought to influence mutation tolerance and cross-reactivity. We present a high throughput method for mapping primary TCR footprints using barcoded tetramers without structure determination.