Supercentenarians show high CD4 CTL levels

A study published in Cell Reports on August 19 found that supercentenarians (people aged 110+) have unusually high levels of CD4 cytotoxic T lymphocytes (CD4 CTLs), a rare type of immune cell that can kill tumor cells. Researchers led by Kosuke Hashimoto of the University of Osaka analyzed blood samples from 28 Japanese adults. The median proportion of CD4 CTLs rose from 4% in people aged 70-99 to 9.6% in centenarians and 17.6% in supercentenarians. The cells showed signs of clonal expansion, with the largest clone averaging 33.3% of CD4 CTLs. Receptor sequences matched those found in cancer patients, suggesting a possible link to cancer surveillance. The study does not prove that CD4 CTLs cause longevity but suggests the immune system may continue adapting in extreme old age. The research was supported by several Japanese institutions.