Penn Compact 2020/

Integrate Knowledge: Exploring Single Cells T-Cells Hunt Like Sharks in Human Body

A cross-disciplinary research team at Penn has arrived at a surprising finding: T cells, which comprise a key part of the immune system, track down parasites using a movement strategy similar to those used by predators such as sharks, monkeys, and blue-fin tuna to hunt prey.

The research, published in the journal Nature, involved a unique collaboration between the laboratories of senior authors Christopher Hunter, professor and chair of the Pathobiology Department at Penn Vet, and Andrea Liu, the Hepburn Professor of Physics in the Department of Physics and Astronomy in the School of Arts and Sciences. Penn Vet postdoctoral researcher Tajie Harris and physics graduate student Edward Banigan also played leading roles in the research.

The study was conducted in mice infected with the parasite Toxoplasma gondii. Using a powerful microscope that can display living tissues in three dimensions in real time, the researchers tracked the movements of T cells.

Contrary to their expectations, the T cells did not move directly toward the parasite. But their movements were not entirely random, either. Instead, the cells’ paths tended to have many short “steps” and occasional long “runs,” with long and short pauses in between.

T cells aren’t the only ones that move this way to find their targets. This strategy—making many short-distance movements interspersed with occasional longer-distance moves—seems particularly common among hunting marine predators, including tuna, sharks, sea turtles, and penguins. Terrestrial species like spider monkeys and honeybees may also use a similar approach to locate rare resources.

This parallel between the T cells and animal predators makes sense because parasites, like animal prey, have evolved to evade detection.

“Many pathogens know how to hide, so T cells are not able to move directly to their target,” Hunter said. “The T cell actually needs to go into an area and then see if there’s anything there.”

Text by Katherine Unger Baillie
Video by Kurtis Sensenig