T Cells Hunt Like Sharks in Our Body [video]

A Penn Study

A cross-disciplinary team at the University of Pennsylvania has arrived at a surprising finding: T cells, a key part of the immune system, use a movement strategy to track down parasites that is similar to strategies that predators such as monkeys, sharks and blue-fin tuna use to hunt their 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 in Penn's School of Veterinary Medicine, and Andrea Liu, the Hepburn Professor of Physics in the Department of Physics and Astronomy. Penn Vet postdoctoral researcher Tajie Harris and physics graduate student Edward Banigan also played leading roles in the research.

The study, published in the journal Nature, was conducted in mice infected with the parasite Toxoplasma gondii. Using a refine yet 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, their 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 —many short-distance movements interspersed with occasional longer-distance moves — seems particularly common among hunting marine predators, including tuna, sharks, zooplankton, sea turtles and penguins, though terrestrial species like spider monkeys and honeybees may use the same approach to locate rare resources.

This parallel with animal predators also makes sense because parasites, like prey species, 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."