Researchers published an article in the journal Cell Reports suggesting that individuals classified as supercentenarians may have a high quantity of a specific type of immune system cell. These cells, known as cytotoxic CD4 cells, could potentially be beneficial in fighting cancer and might contribute to these people reaching very advanced ages.
The study's own authors emphasize that this hypothesis has not yet been confirmed, mainly because this rare cell is understudied and its exact function remains unknown.
For the investigation, scientists from Japanese universities collected data from three groups of participants: eight people aged between 70 and 99, ten people between 100 and 109 years old, and ten individuals aged 110 or older. The findings indicated that the younger group had a normal proportion of these cells, corresponding to 4% of total CD4 T cells. This rate increased to 10% among centenarians and rose to approximately 18% in supercentenarians.
The study highlights the inherent difficulty in monitoring supercentenarians, given that few individuals reach such longevity; in Brazil, for example, there are only 37 thousand people aged 100 or older, and this group shrinks further when considering supercentenarians over 110 years old.
Globally, life expectancy at birth is around 73 years, although this figure varies by region, influenced by factors such as access to basic infrastructure, income level, national development, and lifestyle. In Brazil, the IBGE points to a slightly higher average of 76.4 years.
Even beyond the centenarian mark, these individuals often maintain good quality of life, rarely developing diseases such as cancer, dementia, or heart problems.
Specialized Cells
All possess CD4 T lymphocytes, which are white blood cells responsible for orchestrating bodily defense and are part of the adaptive immune system. Their function is to monitor the body for damaged, infected, or cancerous cells, signaling the problem to other immune cells, such as CD8 T lymphocytes, which then neutralize the target.
There is a rarer subgroup of CD4 cells, called cytotoxic CD4 cells. Although less studied, there is growing evidence that these cells can directly eliminate malignant cells, including those from lung cancer and melanoma, thus acting as killer agents and not just as sentinels.
A previous discovery in 2019 pointed out that these cells tend to multiply as people reach their 90s. The present study sought to quantify how these cells change during the aging process.
Since the cells were detected circulating in the blood, the team could not identify the specific tissues where they reside nor their exact functions. However, by analyzing cellular receptors and comparing them with a CD4 database, about 30 sequences from the study matched those of cancer patients in that database. This suggests that they may be specialized in destroying cancerous cells, even if this action has not been observed.
Some experts call for caution in interpreting these results. Alejandro López-Soto, a biochemist at the University of Oviedo, Spain, stated to Nature that the notion that these cells protect centenarians against cancer is biologically viable and encouraging, but remains speculative until their antigens are identified and direct tumor destruction is proven.
Additionally, some question whether the research sample may be insufficient. However, the researchers argue that the complexity of the scenario must be considered: in Japan, the location of the research, there are only about 150 supercentenarians, making the participation of ten people a significant number in practice.