Rare immune cells surge in supercentenarians, hinting at longevity's cellular secrets

Among the rarest of human beings—those who have lived past 110 years—scientists have discovered an immune system that has not simply endured time but been transformed by it. A population of immune cells called CD4 cytotoxic T lymphocytes, ordinarily a minor presence, has grown into a dominant and surprisingly flexible force in supercentenarians, suggesting that extreme longevity may be less about preservation than about a lifetime of adaptive refinement. Whether these cells are the architects of long life, its byproduct, or merely its signature remains one of biology's more humbling open quest