Two-photon imaging of intratumoral CD8⁺ T cell cytotoxic activity during adoptive T cell therapy in mice
J. Clin. Invest. Béatrice Breart, et al. 118:1390 doi:10.1172/JCI34388 [Go to this article.]

Figure 3
Direct action of CTLs on individual tumor cells drives tumor regression. Mice were injected with a mixture of EL4-mCFP and EG7-mYFP tumor cells. On day 5, some mice were adoptively transferred with 5 × 10⁶ in vitro activated OT-I CD8⁺ T cells. Three days after transfer, tumors were harvested, and confocal imaging was performed on frozen sections. (A) Mice injected with the tumor cell mixture developed chimeric tumors composed of small individual patches of EL4-mCFP and EG7-mYFP cells (left). The transfer of OT-I CTLs resulted in the clearance of EG7-mYFP patches, whereas EL4-mCFP patches appeared minimally affected (middle and right). Scale bars: 100 μm (left and middle); 10 μm (right). (B) The contribution of EG7-mYFP, EL4-mCFP, or other cells (i.e., nonfluorescent cells) to the overall tumor volume was determined from confocal images of frozen tumor sections. Each dot represents the value derived from an individual section. (C) Single-cell suspensions of tumor were analyzed by flow cytometry. The relative percentage of EG7-mYFP and EL4-mCFP cells is shown. Data are gated on tumor cells.