Mito warriors: Scientists discover how T cell assassins reload their
weapons to kill and kill again
New footage shows T cells hunting down and destroying cancer cells

Date:
October 14, 2021
Source:
University of Cambridge
Summary:
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.



FULL STORY ========================================================================== 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 recognise and eliminate threats -- including tumour
cells and cells infected with invading viruses, such as SARS-CoV-2, which causes COVID- 19. They are also at the heart of new immunotherapies that promise to transform cancer treatment.

Professor Gillian Griffiths from the Cambridge Institute for Medical
Research, who led the research, said: "T cells are trained assassins
that are sent on their deadly missions by the immune system. There are
billions of them in our blood, each engaged in a ferocious and unrelenting battle to keep us healthy.

"Once a T cell has found its target, it binds to it and releases
its toxic cargo. But what is particularly remarkable is that they
are then able to go on to kill and kill again. Only now, thanks to state-of-the-art technologies, have we been able to find out how they
reload their weapons." Today, in a study published in Science, the team
have shown that the refuelling 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 micrometres in length, about a tenth
the width of a human hair. The cells 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.

The research was funded by Wellcome.

Video: https://www.youtube.com/watch?v=naMi4lYXm8Q ========================================================================== Story Source: Materials provided by University_of_Cambridge. The original
text of this story is licensed under a Creative_Commons_License. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Lisci, M et al. Mitochondrial translation is required for sustained
killing by cytotoxic T cells. Science, 2021 DOI:
10.1126/science.abe9977 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211014141850.htm

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