Investigating the spatiotemporal organization of CD8 during T cell activation 9234

Abstract Description The spatiotemporal organization of surface receptors and membrane architecture plays a crucial role in T cell activation. Using expansion microscopy (ExM) and TIRF microscopy, we investigated the nanoscale organization of coreceptor CD8 and its distribution relative to the T cell receptor (TCR). In resting T cells, CD8 nanoclusters preferentially localized to microvilli tips while TCR nanoclusters showed no such preference. Upon activation, both CD8 and TCR clusters increased in size and exhibited enhanced colocalization. To examine T cell-tumor cell interactions, we investigated immune synapse formation from early (2 min) to mature (10 min) stages. We observed a significant increase in TCR cluster size and cluster volume occupancy at the synapse compared to the whole cell while CD8 clusters showed no significant changes. Using TIRF microscopy to image T cell activation on activating supported lipid bilayers (SLB), we found that CD8 and TCR clusters converged to the microvilli upon antigen detection. Our findings highlight the distinct spatiotemporal organization of CD8 relative to TCR and the T cell membrane topography. Further work will investigate how this spatiotemporal organization influences T cell signaling. Funding Sources Supported by the Shurl and Kay Curci Foundation; NIH GM133353 Topic Categories Immune Response Regulation: Cellular Mechanisms (IRC)