Scientists who study centenarians say key to living beyond 100 is lots of exposure to infections

It may sound counterintuitive, but scientists say a key to living past 100 is a lot of experience fighting off infections.

Researchers who studied the DNA of seven centenarians found that they all had one thing in common: they had battled many bugs and viruses.

Their subjects had a large number of B cells, immune cells and antibodies needed to defeat old enemies.

Scientists are trying to figure out if catching and beating infections is key, or if centenarians are just genetically stronger in the immune department.

The study’s lead author, Paola Sebastiani, a biostatistician at Tufts University in Boston, said the immune profiles of centenarians show “a long history of exposure to infections and the ability to recover from them.”

“We believe centenarians have protective factors that allow them to survive the Spanish flu and Covid,” she told DailyMail.com

The study, which also involved scientists at Boston University, looked at blood samples from seven centenarians between the ages of 100 and 119.

The team isolated a critical component of the participants’ immune system: peripheral blood mononuclear cells (PBMCs), a type of immune cell that originates in the bone marrow.

The researchers then subjected these immune cells to a series of tests, comparing them to blood samples from two younger subjects, who were neither extremely long-lived themselves nor centenarians in their own family history.

The team noticed a dramatic shift in the centenarians’ immune cell mix: significantly more B cells than CD4+ T cells, indicating that their immune systems had gained decades of hard-won experience fighting natural and environmental infections.

Taken together, the study examined the proportion of 13 subtypes of B cells and T cells, noting a major shift in the ratio from the innate fighters to the more adapted, experienced cell types.

“Centenarians harbor unique, highly functional immune systems that have successfully adapted to a history of insults,” the study concludes, “allowing for exceptional longevity.”

But the scientists can’t yet say definitively whether or not their results show a hereditary predisposition to extremely longevity or if it’s all just evidence of their centenarians’ seasoned immune systems.

“We know there are many hereditary factors common to centenarians,” Sebastiani told the Mail. “We are not (yet) able to make the direct connection between these factors and what we see in their blood, in terms of their immune cell types.”

However, Sebastiani and her team identified 25 specific genes that were much more active in the centenarians, revealing a genetic pattern for extremely longevity.

Among them, they found much greater use of the gene STK17Aknown to be involved in repairing damaged DNA, and HLA-DPA1a gene that makes the antigens needed to tag certain infections in the body.

They also found one gene, S100A4that was all unique to centenarians. S100A4portion of the S100 family studied in age-related disease, is associated with both longevity and regulating metabolism.

Finally, the team’s analysis, published last Friday in The Lancetadmits that ‘we cannot determine whether this EL [Extreme Longevity] specific patterns are the drivers for extreme longevity or the effect of extreme old age.’

The trick, Sebastiani says, will be to develop new studies measuring and observing future centenarians over time, a task already underway.

“We have more than one study where we included descendants of centenarians,” Sebastiani said. “Most of them will become centenarians themselves – and we collect their blood over time.”

“So hopefully we’ll have a better answer to the heritability of these traits soon.”