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Supercentenarians carry unusual abundance of killer immune cells, study finds

A study of individuals aged 110 and older reveals elevated levels of CD4 cytotoxic T lymphocytes, which may adapt to persistent age-related threats.

Updated Aug 25, 2026 · 13:46 UTC1 reports

The short version

  • A study published in Cell Reports on August 19, 2026, found that supercentenarians carry unusually high levels of specialized CD4 cytotoxic T lymphocytes (CD4 CTLs), which are rare immune cells that can kill abnormal cells.
  • The median proportion of CD4 CTLs rose with age, measuring 4% in adults aged 70–99, 9.6% in centenarians aged 100–109, and 17.6% in supercentenarians aged 110 and older.
  • While some of the dominant immune cell receptors matched public sequences from cancer patients, the study does not prove these cells protect against disease or directly cause exceptional longevity.

Key facts

  • Researchers published a study in Cell Reports examining immune cell counts in blood samples from 28 adults across three age groups: 70–99, 100–109, and 110 and older.[ScienceDaily]
  • The median proportion of CD4 CTLs increased with age, from 4% in the youngest cohort to 17.6% in the supercentenarian cohort, suggesting that expansion of these cells may begin around age 100.[ScienceDaily]
  • The study found significant clonal expansion of these T cells, with the largest individual clone representing an average of 33.3% of all CD4 CTLs among participants, and reaching 53.8% in one centenarian.[ScienceDaily]
  • Researchers matched several dominant T cell receptor sequences from participants to database entries from patients diagnosed with lung, breast, and liver cancers, though none of the study participants actually had those cancers.[ScienceDaily]
  • The study's first author is Kosuke Hashimoto, an associate professor at the University of Osaka in Japan.[ScienceDaily]

What remains uncertain

  • The findings do not establish whether high levels of CD4 CTLs actually protect against cancer, directly help people live longer, or how these cells behave inside human tissues beyond the bloodstream.[ScienceDaily]

Sources