AuNP-loaded T cells migrate to tumors in vivo. (A) T cells were retrovirally modified to express firefly luciferase then loaded in the presence of 0.5 nM AuNP for 24 h. Cells were subsequently injected intravenously into SCID mice bearing subcutaneous xenografted LCL tumors. Bioluminescent imaging of AuNP-T cell biodistribution at 48 h post-injection showing AuNP-T cell localization at the tumor site (red circle) and within the spleen. (B) Resected tumors were analyzed by bright field imaging (top row) and immunohistochemistry for human CD3 expression and dark field imaging (bottom row) to indicate the presence of AuNPs. Red arrows indicate the colocalization of CD3+ T cells and AuNPs within the tumor.