Immune Systems of 110-Year-Olds

Recent research published on August 19, 2026, in the Cell Press journal Cell Reports reveals that the immune systems of supercentenarians aged 110 and older harbor a remarkable secret involving the notable expansion of rare CD4 cytotoxic T lymphocytes (CD4 CTLs), which are known to kill tumor cells in certain cancers. Led by associate professor Kosuke Hashimoto at the University of Osaka, the study demonstrates that immune aging is not merely a process of progressive decline, but that the immune system can continue actively adapting to age-related challenges even at extreme old age through the selective clonal expansion of specific T cells. Researchers analyzed blood samples from 28 adults divided across three age groups of 70 to 99, 100 to 109, and 110 and older, discovering that median CD4 CTL levels rose steadily from 4% to 9.6% and reached an impressive 17.6% in supercentenarians, driven significantly by clonal expansion where a single clone reached up to 53.8% in one centenarian. While the exact targets of these dominant CD4 CTL clones remain open questions, sequence comparisons with public databases matched nearly three dozen entries from cancer patients with lung, breast, and liver cancers, suggesting that these cells may provide early immune adaptation and protection against abnormal or senescent cells to promote exceptional longevity.