NSOM/QD-based nanoscale immunofluorescence imaging of antigen-specific T-cell receptor responses during an in vivo clonal Vγ2Vδ2 T-cell expansion

Nanoscale imaging of an in vivo antigen-specific T-cell immune response has not been reported. Here, the combined nearfield scanning optical microscopy- and fluorescent quantum dot-based nanotechnology was used to perform immunofluorescence imaging of antigen-specific T-cell receptor (TCR) response in an in vivo model of clonal T-cell expansion. The near-field scanning optical microscopy/quantum dot system provided a best-optical-resolution (<50 nm) nanoscale imaging of V gamma 2V82 TCR on the membrane of nonstimulated V gamma 2V delta 2 T cells. Before Ag-induced clonal expansion, these nonstimulating V gamma 2V delta 2 TCRs appeared to be distributed differently from their alpha beta TCR counterparts on the cell surface. Surprisingly, V gamma 2V delta 2 TCR nanoclusters not only were formed but also sustained on the membrane during an in vivo clonal expansion of V gamma 2V delta 2 T cells after phosphoantigen treatment or phosphoantigen plus mycobacterial infection. The TCR nanoclusters could array to form nanodomains or microdomains on the membrane of clonally expanded V delta 2V delta 2 T cells. Interestingly, expanded V gamma 2V delta 2 T cells bearing TCR nanoclusters or nanodomains were able to rerecognize phosphoantigen and to exert better effector function. These studies provided nanoscale insight into the in vivo T-cell immune response.