CD8 T cells are part of the acquired immune system, that is, the part of the body’s own defense system that is continually developed over the course of life by dealing with pathogens of all kinds. When this cell subtype becomes active, the immune cells release molecules into their environment that trigger inflammation or initiate cell death. It is actually their job to act against cells infected with viruses or cancer cells.
The team led by Bernese Tony Wyss-Coray and David Gate from Stanford University (USA) has now found that a subtype of these CD8 T cells is more common in patients with Alzheimer’s or a precursor to it.
Salzburg researchers had noticed these cells in mouse brains some time ago, while regardless of this, the colleagues from the USA found what they were looking for in the blood and brain fluid of sick people. The researchers first noticed the connection at a specialist conference, after which they intensified their collaboration.
Elsewhere, cells are “armed”
“There is every indication that these cells appear to be activated outside the brain, that is, they are activated. When they arrive in the brain, they are ‘unlocked’ and given the ‘license to kill'”, said the Salzburg neuroscientist Ludwig Aigner, who was involved in the publication ,
They are apparently particularly active in the hippocampus, the region of the brain that is central to remembering. The trigger of Pfeifferer’s glandular fever, the Epstein-Barr virus, may also play a role in the process of arming the CD8 T cells.
What are the cells doing in the brain?
“We are interested in the question of what these cells actually do in the brain and whether they actually promote neuropathology,” said Aigner. Initial evidence suggests that they actually affect brain function. “It can be assumed that they destroy neurons there, but we don’t know yet,” said the scientist.
However, their presence could also help diagnose Alzheimer’s in combination with other factors in the future. If CD8 T cells actually turn out to be disease drivers, the course of their blockage could be influenced during therapy.
* Technical article links https://doi.org/10.1038/s41586-019-1895-7; https://doi.org/10.1038/d41586-019-03892-8