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Why do people who live past 100 have so many of these immune cells?
People who live past 100 carry far more of one kind of immune cell — a cell that hunts down damaged cells and kills them. Nobody knows yet if that is the reason they live so long. Our first job is simple: find out whether we can count these cells reliably in ordinary adults here in Phoenix.
The cell we are counting
A helper immune cell that has picked up the tools to kill damaged cells directly.
Ages 70–99
The starting point. In older adults who are not unusually long-lived, only about 4 out of every 100 of these immune cells are the killer type.
Centenarians (100–109)
In people who reach 100, that number more than doubles. It happens often enough across different people that it is worth measuring properly.
Ages 110+
In the oldest people of all, these killer cells are everywhere — and large groups of them look like copies of each other, as if they have been fighting the same thing for decades.
Median proportion of cytotoxic CD4 T lymphocytes among CD4 T cells. Hashimoto K. et al., Cell Reports, 19 August 2026 — 28 adults aged 70 and older.
The Scientific Foundation
“Some of the most highly expanded T-cell receptor sequences matched sequences previously seen in tumor-associated T cells — in people who had never had those cancers.”
In plain terms: some of these immune cells looked like cells that fight cancer — in people who never had cancer. That hints that a few people may be quietly clearing bad cells long before a tumor could ever be found. The scientists are careful here. They suggest it. They have not proven it.
Our response is deliberately small. We are not building a clinic. We are asking a Phoenix lab to repeat the same measurement on blood from ordinary adult volunteers, and to tell us how much the numbers differ from one person to the next.
Joe DiDonato
Project Sponsor · Phoenix, AZ