People who live past 110 possess a rare immune system trait that produces a disproportionately high number of specialized cells to fight cancer and infections, according to a new Japanese study.
Research from Osaka University, published in the journal Cell Reports, found that rather than inevitably weakening with age, the immune systems of supercentenarians actively multiply CD4 cytotoxic T-lymphocytes to neutralize viruses, inflammation and cancerous cells.
Researchers said this overperforming immune system appears to explain their extreme longevity. Supercentenarians are people who live to be older than 110. It is estimated that only one in 2 million to 5 million people reach this age.
Age group analysis
The study examined 28 volunteers across three age groups, analyzing more than 40,000 immune system cells. The groups included eight people aged 70 to 99, ten centenarians aged 100 and older, and ten supercentenarians.
Lead researcher Dr Kousuke Hashimoto, an associate professor of bioinformatics at Osaka University, said the sample size of ten supercentenarians was significant given there are only 150 people of that age living in Japan.
The research showed that as the participants' age increased, so did the number of CD4 cytotoxic T-lymphocytes, or CD4 CTLs. This number peaked in the supercentenarian group.
Adaptive cell response
CD4 CTLs are a type of white blood cell that coordinate the immune response to infections. While extremely rare in most people, the study found these cells begin to clone themselves once a person passes 100 years of age.
Rather than simply activating the immune system, the cells directly destroy the causes of infections, targeting viruses, inflammation and cancer.
Hashimoto said this increase was not a passive consequence of aging, but reflected an active adaptive response to persistent antigens. He said it was surprising that the immune system maintained this adaptive capacity after a century of life.
This ability was unique considering supercentenarians faced persistent challenges that accumulated gradually over many decades, Hashimoto concluded.
The scientists later verified their findings by analyzing the immune systems of 1,500 other people of various ages, reaching the same conclusions. Previous studies had shown that CD4 CTLs target inflammation and fight cell aging.
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