The TCR is randomly distributed on the plasma membrane of resting antigen-experienced T cells

It is the main function of T cells to identify harmful antigens as quickly and precisely as possible. Super-resolution microscopy data has indicated that global clustering of the T cell receptor (TCR) occurs prior to T cell activation. Such pre-activation clustering has been interpreted as representing a potential regulatory mechanism that fine-tunes the T cell response. We found here that apparent TCR nanoclustering could be attributed to overcounting artifacts inherent to single-molecule-localization microscopy. Using complementary super-resolution approaches and statistical image analysis, we found no indication of global nanoclustering of the TCR on antigen-experienced CD4(+) T cells under non-activating conditions. We also used extensive simulations of super-resolution images to provide quantitative limits for the degree of randomness of the TCR distribution. Together, our results suggest that the distribution of TCRs on the plasma membrane is optimized for fast recognition of antigen in the first phase of T cell activation.