Mito Warriors: New Footage Shows T Cell Assassins Hunting Down and Destroying Cancer Cells

T Cell Assassins

Credit: University of Cambridge

Scientists discover how T cell assassins reload their weapons to kill and kill again.

Cambridge researchers have discovered how T cells – an important component of our immune system – are able keep on killing as they hunt down and kill cancer cells, repeatedly reloading their toxic weapons.

Cytotoxic T cells are specialist white blood cells that are trained by our immune system to recognize and eliminate threats – including tumor cells and cells infected with invading viruses, such as

Today, in a study published in Science, the team have shown that the refueling of T cells’ toxic weapons is regulated by mitochondria. Mitochondria are often referred to as a cell’s batteries as they provide the energy that power their function. However, in this case the mitochondria use an entirely different mechanism to ensure the killer T cells have sufficient ‘ammunition’ to destroy their targets.

Professor Griffiths added: “These assassins need to replenish their toxic payload so that they can keep on killing without damaging the T cells themselves. This careful balancing act turns out to be regulated by the mitochondria in T cells, which set the pace of killing according to how quickly they themselves can manufacture proteins. This enables killer T cells to stay healthy and keep on killing under challenging conditions when a prolonged response is required.”

To accompany the study, Professor Griffiths and colleagues have released footage showing killer T cells as they hunt down and eliminate cancer cells.

One teaspoon full of blood alone is believed to have around 5 million T cells, each measuring around 10 micrometers in length, about a tenth the width of a human hair. The cells, seen in the video as red or green amorphous ‘blobs’, move around rapidly, investigating their environment as they travel.

When a T cell finds an infected cell or, in the case of the film, a cancer cell, membrane protrusions rapidly explore the surface of the cell, checking for tell-tale signs that this is an uninvited guest. The T cell binds to the cancer cell and injects poisonous ‘cytotoxin’ proteins down special pathways called microtubules to the interface between the T cell and the cancer cell, before puncturing the surface of the cancer cell and delivering its deadly cargo.

Reference: “Mitochondrial translation is required for sustained killing by cytotoxic T cells” by Lisci, M et al., 14 October 2021, Science.


DOI: 10.1126/science.abe9977

The research was funded by Wellcome.