Naive T cells live in the bone marrow the way recruits live in a barracks. They wait for the order to attack the enemy. But with age, cells carrying a special tag, the ANXA1 protein, start showing up among them. That tag works like a brake shoe: the cell can't charge into battle.
Scientists examined the bone marrow of 15 people aged 3 to 91. It turned out that the older the person, the more of these held-back cells there are. They don't just sit idle: they also release substances that cause inflammation and speed up aging. When the gene responsible for ANXA1 was removed from mice, their T cells became more active and killed cancer cells better. And when old mice received T cells without ANXA1, those cells wiped out senescent cells throughout the body. The mice grew stronger and lived longer.
So a simple tag on a cell turned out to be an important brake on immunity. If we learn to remove that tag, we can help the body fight aging on its own.
The median lifespan of mice receiving ANXA1- CD8+ naive T cells increased by more than 30 weeks, which translates to roughly 100 human years.
The idea of rejuvenation through transfusion of young immune cells echoes Aldous Huxley's novel Brave New World, where youth is maintained through hormone therapy, and the 2015 film The Immortals, where blood transfusions from young donors halt aging.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.