Archive · 21 Aug 2026
Unusual Killer Immune Cells May Help Some People Reach 110
Scientists studied immune cells from people of different ages.
They found that people who lived to 100 or 110 had more unusual “killer” immune cells.
These cells are called CD4 cytotoxic T lymphocytes.
They can attack infected, damaged or abnormal cells.
The cells became especially common in people aged 100 and older.
Many copies of some cells suggested that the body had repeatedly encountered certain threats.
The researchers think this may help explain how some very old people continue defending themselves against disease.
However, the study does not prove that these cells cause long life or prevent cancer.
Japanese researchers found unusually high levels of CD4 cytotoxic T lymphocytes in people aged 100 and older.
These cells made up 4% of T cells in adults aged 70-99, 9.6% in centenarians and 17.6% in supercentenarians.
The study analyzed 43,584 T cells from 28 Japanese participants, including 10 people aged at least 110.
CD4 cytotoxic T cells showed substantial clonal expansion, suggesting repeated stimulation by persistent antigens.
Researchers cautioned that the cells may support immune surveillance or cause tissue damage, and their role in longevity remains unproven.
- Who
- Researchers led by Kosuke Hashimoto of the Institute for Protein Research at the University of Osaka, with scientists from RIKEN, Keio University and Human Technopole.
- What
- A study examined unusually abundant CD4 cytotoxic T lymphocytes in centenarians and supercentenarians.
- When
- The latest study was reported alongside related research published in 2019, 2023 and 2024.
- Where
- The participants were Japanese, and the research involved institutions in Japan and Italy.
- Why
- Researchers sought to understand how some people remain healthy and avoid or delay age-related diseases into extreme old age.
- Participants
- 28 Japanese people: eight aged 70-99, 10 centenarians and 10 supercentenarians.
- Cells analyzed
- 43,584 T cells.
- CD4 CTLs in adults aged 70-99
- Median of 4% of T cells.
- CD4 CTLs in centenarians
- Median of 9.6% of T cells.
- CD4 CTLs in supercentenarians
- Median of 17.6% of T cells.
- Largest cell clone
- An average of 33.3% of CD4 CTLs.
- Cancer-sequence matches
- 32 of 36 matching expanded sequences were found in cancer samples, although the studied participants had no known history of those cancers.