Japanese researchers discovered a few years ago that people over 110 years old have an unusual amount of cytotoxic CD4 T lymphocytes, a rare type of immune cell that, in addition to coordinating other defense cells, can directly kill dangerous cells in the body. A new study published in the journal Cell Reports, led by Hashimoto and colleagues, attempted to understand how these cells appear during aging, analyzing 28 participants from different age groups.
The results reveal a significant change: between 70 and 99 years of age, these cells represented only 4% of T lymphocytes on average. Among centenarians between 100 and 109 years of age, the proportion rose to 9.6%, and in supercentenarians aged 110 or older it reached 17.6%, more than four times the value of the younger group. Furthermore, many of these cells were copies or clones of each other, with the most abundant clone representing on average one third of all cytotoxic CD4 T lymphocytes.
The researchers raise the hypothesis that these cells may be fighting cancer cells, since some of their genetic characteristics are similar to those of T cells that expand within tumors, especially in lung cancer. However, the study did not directly demonstrate that these cells are killing cancer cells, and their true targets are still not known with certainty.
The article concludes that, although aging is often described as a story of loss, supercentenarians may represent an example of how the body continues to grow and adapt. Perhaps reaching 110 years does not depend only on preserving the defenses of youth, but also on the capacity to build new defenses against problems that only arise after a century of life.
