, Aug. 25 -- People who live to exceptionally old ages may have immune systems that continue adapting to new health threats, according to a new study.

Researchers have found that supercentenarians - people aged 110 or older - have unusually high levels of specialised immune cells known as CD4 cytotoxic T lymphocytes (CD4 CTLs).

These rare immune cells can kill certain tumour cells and multiply quickly when the body faces an infection. The findings, published August 19 in the Cell Press journal Cell Reports, suggest that this immune response may be linked to healthy ageing in people who reach extreme old age.

"Immune ageing is not simply a process of decline," said Kosuke Hashimoto, an associate professor at the University of Osaka in J...