Movies captured with the two-photon microscope then recorded the unfolding scene in the so-called tumor microenvironment. How would the green T cells behave in the two groups of mice?
"In the animals that received the vaccination, we saw two waves of activity after the T cells entered the tumor microenvironment," Weninger says. "Early on, the T cells didn't actively migrate through the tissue. This, we found, was because they were interacting directly with the tumor cells in place. In several instances, we were actually able to see the tumor cells dying ?the first time that has ever been observed in real-time in living animals. Then, once the tumor cells had been destroyed, we saw a dramatic change in the behavior of the activated T cells. They began to migrate actively, searching for any other tumor cells that might remain in the area."
In contrast, in the mice that did not receive the vaccination, the T cells were much sparser and, importantly, distinctly inactive in their migration. Consequently, tumor cell death was very rare under these conditions.
The researchers then designed a second set of experiments to complement the first. In the first set of experiments, the T cells were varied in two groups of mice while the target tumor cells were uniform. In the second set, the T cells were uniform while the tumor cells varied in two groups of mice according to whether or not they presented a specific antigen to which the T cells would respond.
T cells were removed from mice without tumors, activated in the test tube, and then reintroduced into mice carrying tumors that either did or did not express the antigen. This procedure, referred to as adoptive transfer, is an immunotherapy strategy against cancer being tested in a number of human clinical trials. In some of those trials, a patient's own T cells are removed, tested for their ability to recognize the patient's cancer cells, activated and expa
Source:The Wistar Institute