Immunity system complexity: supporting T cells. (Introduction)

by David Turell , Friday, January 13, 2023, 18:26 (470 days ago) @ David Turell

Immune cells support telomeres in T cells:

https://www.the-scientist.com/news-opinion/t-cells-ward-off-aging-with-help-from-their-...

"Like all of the cells in our body, immune cells age. Over time, they become less and less able to fight infection, cancer, and disease. Previously, researchers thought the process of cells growing old and feeble, known as cellular senescence, was an inevitable consequence of routine infection and time. But a study published yesterday in Nature Cell Biology suggests that an interaction between T cells and antigen presenting cells (APCs) early in the immune response to viruses may determine how fast T cells decline.

"Telomeres are long, repeating sequences of DNA that bookend chromosomes and protect their ends from fraying. As cells age, their telomeres get shorter and shorter with each cell division until eventually, they can no longer divide. The new study finds that after infection, APCs, the cells that initially kickstart T cells’ immune response by presenting them with a foreign antigen, chop off and deliver their telomeres to T cells, the white blood cells that fight viruses.

"The researchers found that when APCSs deliver their telomeres to T cells, the latter shift into stem cell-like configuration, which delays their senescence. The researchers also found that this interaction boosts long-term immunity in mice, suggesting that this finding could pave the way for more efficient vaccination.

***

"When a foreign invader such as a virus enters the body, T cells rapidly divide, and their numbers skyrocket. Previously, scientists knew that T cells employ telomerase, an enzyme that extends telomeres, to combat telomere loss during this rapid division, which over time can lead to shortened telomeres and eventual senescence. But telomerase isn’t sufficient to prevent T cell senescence, sending scientists searching for another key mechanism responsible for guarding against T cell aging.

***

"Previous studies from other groups had determined that in the more stem cell­–like configuration, T cells live longer than those that have differentiated, says Lanna. The results suggest that the fate of some T cells—whether they become senescent or not—is determined when APCs deliver telomeres to T cells. This means that some T cells’ destinies are sealed before the immune response has even started. “That’s against dogma in the field of immune senescence,” says Lanna.

***

"The researchers also observed that APCs deliver telomeres to some T cells and not others, although it’s not clear why. Using Flow-FISH, an assay that counts cells and analyzes their telomere length one by one, the team found that naive T cells—cells that have never encountered an antigen—and memory T cells were more likely to take up telomeres. Meanwhile, various types of effector T cells are less likely to do so."

Comment: this mechanism is the basis of fighting invaders. It must be very ancient in evolution, as all organisms must have it to survive. It did not evolve stepwise from repeated encounters with infection. In my view God set it up in the beginning of life. We see T cells and B cells are given purposefully distinct specific jobs, Not by chance.