Reached the age of 110: scientists discover unusual immune cells in the blood of long-lived people
How do some people manage to live over 100 years and successfully resist aging processes? A new study published in the journal "Cell Reports" points to the important role of the immune system. Long-lived individuals were found to have an increased level of rare immune cells capable of destroying damaged and cancerous cells.
How do some people manage to live more than 100 years and cope for so long with diseases and aging processes? A new study published in the scientific journal "Cell Reports" found a possible clue in the immune system. The researchers discovered that in people aged 100 and over, there was a relatively large amount of a rare type of immune cell capable of detecting and destroying damaged, infected, and even cancerous cells. In people who passed the age of 110, the phenomenon was even more pronounced.
As a person ages, the body has to deal with more cells that have been damaged or changed, and at the same time, the risk of various diseases increases. It is commonly thought that the immune system also gradually weakens over the years, but the new study suggests that the picture may be more complex.
The researchers examined a specific type of white blood cell called CD4 T cells. Usually, these cells serve as a kind of "manager" of the immune system: they do not necessarily attack the threat themselves, but help the body activate and direct the immune response. However, a small portion of these cells has a different ability. These are cells known as CD4 CTLs, which are capable of directly attacking other cells in the body – for example, cells that have been infected, damaged, or have become cancerous. Usually, such cells are found in the body in small quantities. In the very elderly people examined in the study, however, the researchers found many more of them.
28 people from Japan of various ages participated in the study. Among eight subjects in their 70s, 80s, and 90s, the proportion of these rare immune cells was at a median of about 4%. Among ten people aged 100 and over, the rate already reached 9.6%. Among people who passed the age of 110, another jump was found, and the median rate reached 17.6%.
In simple terms: the older the participants, the higher the proportion of immune cells capable of destroying problematic cells the researchers usually found. However, the phenomenon is not uniform in everyone. One of the participants who had not yet reached the age of 100 actually had the highest proportion of these cells among all the subjects. Therefore, it cannot be said that there is a direct and simple connection between the number of cells and the number of years of life.
The researchers discovered something else: the immune cells found in the very elderly were still active. That is, it was not just about cells that had accumulated in the body over the years but were no longer able to perform their function. According to immunologist Kosuke Hashimoto from Osaka University, "Immune aging is not just a process of deterioration. The selective expansion of certain T cells suggests that even at a very advanced age, the immune system may continue to adapt to age-related challenges."
Instead of the immune system just getting weaker, it is possible that in some people it changes itself to deal with the threats that accumulate in the body over the years. The researchers even tracked the change that the cells undergo. They found that the immune cells start as "helper" cells, but later gradually lose two proteins found on the cell surface – CD27 and then CD28 – and acquire properties that allow them to act as cells that attack and destroy other cells.
Another finding provided a clue that the immune system of long-lived people not only holds more such cells but also multiplies them in response to threats. When a T cell identifies a specific threat, it can create many copies of itself. This is exactly what the researchers found in the blood of the elderly participants. On average, about a third of the CD4 CTLs found were copies originating from a single cell. In one of the 100-year-olds, about half of the cells of this type were copies of the same cell. The finding may indicate that the immune system identified certain threats over the years and responded by creating a large number of cells adapted to deal with them.
Is this what allows them to live more than 100 years? This is the central question, and there is still no answer to it. Since the immune cells examined are capable of destroying problematic cells, the researchers raise the possibility that their abundance gives very elderly people an advantage in dealing with these dangers.
Hashimoto explained: "As we age, abnormal cells, including aging cells and cancerous cells, become more common. Our findings suggest that the immune system's adaptation to these changes may contribute to extraordinary longevity." But it is important to emphasize: the study did not prove that these immune cells are the reason why the subjects reached the age of 100 or 110. It is possible that the cells do indeed help them cope better with diseases, but there is also the opposite possibility – that people who manage to live a long time for other reasons develop a larger amount of these cells over the years.
