Overview
- The Cell Reports paper published Wednesday found that a rare cytotoxic subset of CD4 T cells becomes much more common in people aged 100 and older.
- Researchers analyzed blood from 28 Japanese adults using single‑cell transcriptomes, surface protein profiling and T‑cell receptor sequencing to map the T‑cell pool.
- The share of CD4 cytotoxic T lymphocytes rose from a median of about 4% in 70–99‑year‑olds to 9.6% in centenarians and 17.6% in supercentenarians, with frequent large clonal expansions.
- Many dominant T‑cell receptor sequences matched entries previously seen in patients with lung, breast or liver cancers even though study participants had no cancer diagnoses.
- Authors stress the results are correlative, note limits of a small Japan‑only, blood‑only cohort, and say follow‑up tissue and functional studies are needed to test whether these cells actively detect or suppress early tumours.