Sport, balanced diet, low alcohol consumption… If ordinary mortals tend to believe that a healthy lifestyle is the secret to great longevity, the key is actually inscribed in our immune system. This is revealed by a study conducted in Japan.
The Fountain of Youth suddenly seems less legendary. About twenty researchers from Japanese establishments RIKEN Center for Integrative Medical Science (IMS) and Keio University School of Medicine have found the secret of longevity: an excess of CD4 cytotoxic T lymphocyte immune cells.
If studies had already shown that supercentenarians (people who have reached or exceeded the age of 110) were relatively immune to infections and cancers, scientists have taken a close interest in their immune system in a study published by the journal Proceedings of the National Academy of Sciences of the United States of America.
80% cytotoxic cells in supercentenarians
By working on circulating cells of the immune system of seven supercentenarians and five people between the ages of 50 and 80, the researchers found that the number of B lymphocytes was lower in the supercentenarians, but that of T lymphocytes was about the same.
Specifically, the number of cells belonging to a subgroup of T cells was higher in supercentenarians. By analyzing them, the scientists found that they had an extremely high level of cytotoxic cells (sometimes reaching 80% of T cells, compared to 10-20% for the control group).
A process of clonal expansion
However, normally, T cells with the CD8 marker are cytotoxic, while those with the CD4 marker are not. Thus, the team concluded that the CD4+ T cells had acquired cytotoxic status. Similarly, in the control group, there were relatively few cytotoxic CD4+ T cells, indicating that this was not a marker of youth but a characteristic of supercentenarians.
By re-analyzing the blood cells of two supercentenarians, the researchers found that they resulted from a process of clonal expansion, meaning that many cells came from a single cell.
“New Perspectives”
“CD4+ T cells generally function by secreting cytokines, while CD8+ T cells are cytotoxic and it could be that the combination of these two characteristics allows these individuals to be particularly healthy, explains Piero Carninci, one researchers in charge of the study, in a article published on the RIKEN Center for Integrative Medical Science (IMS) website. We believe that these types of cells, which are relatively rare in most people, even young people, are useful in fighting established tumors and could be important for immunosurveillance. It’s exciting and has given us new insights into how people who live very long lives are able to protect themselves from afflictions like infections and cancer.”
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