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

Abstract

Nanoscale imaging of an in vivo antigen-specific T-cell immune response has not been reported. Here, the combined near-field scanning optical microscopy- and fluorescent quantum dot-based nano-technology 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 Vγ2Vδ2 TCR on the membrane of nonstimulated Vγ2Vδ2 T cells. Before Ag-induced clonal expansion, these nonstimulating Vγ2Vδ2 TCRs appeared to be distributed differently from their αβ TCR counterparts on the cell surface. Surprisingly, Vγ2Vδ2 TCR nano-clusters not only were formed but also sustained on the membrane during an in vivo clonal expansion of Vγ2Vδ2 T cells after phosphoantigen treatment or phos-phoantigen plus mycobacterial infection. The TCR nanoclusters could array to form nanodomains or microdomains on the membrane of clonally expanded Vγ2Vδ2 T cells. Interestingly, expanded Vγ2Vδ2 T cells bearing TCR nanoclusters or nan-odomains were able to rerecognize phos-phoantigen and to exert better effector function. These studies provided nanoscale insight into the in vivo T-cell immune response. © 2008 by The American Society of Hematology.