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 2
Visualization of intratumoral CTL dissemination during adoptive T cell therapy. (A and B) In vitro, but not in vivo, primed CTLs massively infiltrated the EG7 tumors. The distribution of intratumoral CTLs (white) was visualized and quantified on frozen sections of EG7 tumor after adoptive transfer of naive or in vitro activated OT-I CD8⁺ T cells. (A) CTLs were counted in multiple individual areas of the tumor encompassing a fixed volume of 500 × 500 × 10 μm. The percentage of tumor areas containing the indicated number of CTLs is shown. The response mounted by in vivo primed OT-I CD8⁺ T cells resulted in a lower and less homogenous CTL infiltrate than did that mounted by in vitro activated CD8⁺ T cells at all time points analyzed. (B) Representative images showing CTL infiltration after transfer of naive or activated OT-I CD8⁺ T cells. (C) Dissemination of in vitro primed CTLs occurred concomitantly with tumor cell elimination. Two days after adoptive transfer of in vitro activated OT-I CD8⁺ T cells, CTLs (red) accumulated in the vicinity of tumor microvessels (white, stained for PECAM). On day 3, CTLs were more evenly distributed, and many EG7 tumor cells had been eliminated. Note that CTL-rich areas tend to have a lower density of EG7 tumor cells (yellow). Scale bars: 100 μm.