The puzzle of how some people live healthily for 100 years or more may have finally been answered by scientists.
Tests have shown that the blood of super-agers is stocked with unusually potent immune cells which personally attack viruses, bacteria or tumours.
Most people carry a type of cell known as CD4 T-cells, which mostly work like sentinels, scouting around for invaders, then pumping out chemicals to attract the ‘soldier’ immune cells which wipe out the disease.
But a study of seven supercentenarians - all of whom lived to 110 or older - found that a large number of their CD4 T-cells take up arms themselves against pathogens, giving a huge boost to the immune system.
Researchers found that the super-agers contained far more of those kinds of cell, around 25 per cent, compared with less than 10 per cent, for the average person.
Dr Kosuke Hashimoto, of the Riken Center for Integrative Medical Science (IMS), in Japan,said: “We were especially interested in studying this group of people, because we consider them to be a good model of healthy aging, and this is important in societies like Japan where aging is proceeding rapidly.”
If we can find the link between the immune system and aging and longevity, we may be able to contribute to prolonging healthy life expectancies.
In Britain the average lifespan for men is 79 for men and 82 for women. In contrast, supercentenarians are are extremely rare and only around 150 people in Britain have lived to 110 or beyond.
The oldest known British person ever was Charlotte Hughes who died in 1993 at the age of 115 years, 228 days
The oldest living Briton is now Hilda Clulow, 111, who was born in Birmingham in England, following the death of Grace Jones, 112, in June.
Mrs Jones, who lived through 26 prime ministers, five monarchs and survived both world wars attributed her longevity to a daily dram of Famous Grouse whisky.
But the new study suggests that a super-protective immune system could be the real reason for extraordinary longevity.
Previous studies have shown that supercentenarians are better able to fight off infections and cancer, which led researchers to wonder if their immune system was fundamentally different.
The Japanese team looked at more than 40,000 circulating immune cells from a group of super-agers, and compared them to younger controls aged between 50 and 80.
Researchers found that the supercentenarians had a very high level of cells that are cytotoxic, meaning that they can kill other cells, sometimes amounting to 80 percent of all T-cells - an important kind of immune cell - compared to just 10 or 20 percent in the controls.
To look at how these special cells were produced, the team examined the blood cells of two supercentenarians in detail, and found that most had been cloned from one single ancestor cell.
IMS Deputy Director Piero Carninci, said: “We believe that this type of cells, which are relatively uncommon in most individuals, even young, are useful for fighting against established tumors, and could be important for immunosurveillance.
“This is exciting as it has given us new insights into how people who live very long lives are able to protect themselves from conditions such as infections and cancer.”
The researchers now want to find out how the supercentenarians acquire the specialist cells and if it could be recreated to boost health and extend life.
The new research was published in the journal Proceedings of the National Academy of Sciences.