People who live beyond 110 carry unusual populations of cancer-killing immune cells, study finds
People aged 110 years and older have large populations of a rare type of immune cell that can kill cancer cells, according to a study published in Cell Reports and reported by Nature on 19 August 2026. The cells — CD4 cytotoxic T lymphocytes (CD4 CTLs) — might help explain why supercentenarians not only live extraordinarily long lives but also seem largely to fend off diseases of old age such as heart disease, dementia and cancer, though the authors caution a protective role has yet to be proved.
By Source Reporters Newsdesk
Thu, 27 August 2026 · 2 min read
People aged 110 years and older have large populations of a rare type of immune cell that can kill cancer cells, according to a study published in Cell Reports and reported by Nature on 19 August 2026. The cells — CD4 cytotoxic T lymphocytes (CD4 CTLs) — might help explain why supercentenarians not only live extraordinarily long lives but also seem largely to fend off diseases of old age such as heart disease, dementia and cancer, though the authors caution a protective role has yet to be proved.
The work, led by biologist Kosuke Hashimoto of the University of Osaka, builds on the team's earlier 2019 finding that supercentenarians harbour relatively large numbers of these rare killer T cells. CD4 CTLs normally make up less than 5% of the body's total T cells, are commonly detected during viral infections, and there is growing evidence they can destroy cancer cells including lung cancer and melanoma cells. "Most of immune ageing research has focused on decline," Hashimoto told Nature. "Our study suggests that even at extreme old age, the immune system may still selectively adapt."
Because so few people reach 110, supercentenarians are difficult to study — only about 150 people aged 110 or older live in Japan, where the study took place. The team enrolled 28 participants: eight people aged 70–90, ten centenarians (100–109), and ten supercentenarians. While younger participants had CD4 CTLs making up around 4% of their T cells, the proportion rose to roughly 10% in centenarians and about 18% in supercentenarians, suggesting this immune adaptation begins around age 100.
Genetic sequencing of the cells' receptors showed the populations were responding to specific, persistent immune threats rather than expanding randomly. In one centenarian, 53.8% of CD4 CTLs were identical clones. When the team compared receptor sequences against a database of CD4 receptors, around 30 matched sequences from people with cancer — most frequently lung cancer — even though none of the study participants had ever had cancer.
The researchers note limitations: because the cells were sampled from circulating blood, the team could not determine which tissues they enter or exactly what they do there. If future work confirms the cells' anti-cancer role, the findings could point toward therapies or biomarkers that help more people stay healthy into extreme old age.
**Sources:** Nature
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