Abstract 488: Direct real-time visualization and quantification of T cell receptor dynamics

Abstract

Abstract The mechanism by which a T cell utilizes its T-cell receptors (TCRs) to recognize foreign peptide major histocompatibility complexes (pMHCs) has not yet been fully deciphered. Much contention still exists surrounding TCR nanostructures before, during, and after synapse formation. Accurate measurements of single TCR location, diffusion/trafficking, clustering, and signaling at the live T-cell membrane have been hindered by the microscopy techniques available. Recently developed Lattice Light-Sheet Microscopy uses a structured light sheet to excite fluorescence in successive planes of a living T cell such that it can record 4D (x, y, z directions and time) images with exceptionally high temporal resolution (10ms/frame, ~1s/volume), finally allowing for precise single molecule tracking. Here we show that TCRs pre-exist in small microclusters prior to synapse formation in both naïve and stimulated resting CD4+ T cells. These clusters are very fast-moving, explaining the previous difficulties of tracking TCR motion and revealing a fast responding mechanism for antigen recognition. Upon encountering antigens, these smaller TCR nanoclusters traffic globally and quickly to the cell interface, aggregate into larger microclusters, and form the immunological synapse. Finally, we compare and contrast the receptor dynamics of CAR-T cells with those of naturally occurring T cell receptors. These findings precisely quantify TCR and CAR dynamics three-dimensionally, suggesting new mechanistic details of the speed and accuracy of TCR signaling and providing new information upon which to base future immunotherapies. Citation Format: Jillian N. Rosenberg, Guoshuai Cao, Fernanda Borja-Prieto, Yanran He, Hans Schreiber, Jun Huang. Direct real-time visualization and quantification of T cell receptor dynamics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 488.