The study published in Cell Reports on August 19 reveals that supercentenarians, individuals aged 110 or older, exhibit unusually high levels of CD4 cytotoxic T lymphocytes (CD4 CTLs) in their immune systems. These specialized immune cells, previously known for their ability to kill tumor cells in certain cancers, can rapidly reproduce through clonal expansion, aiding the immune response to infections. The research indicates that the proportion of CD4 CTLs increases steadily with age, rising from 4% in adults aged 70-99 to 17.6% in those aged 110 and older, suggesting that the expansion of these cells may begin around age 100.

Further analysis of the participants’ T cell receptors revealed that clonal expansion plays a significant role in the abundance of CD4 CTLs among older adults. The largest individual clone represented an average of 33.3% of all CD4 CTLs, with one centenarian showing a single clone comprising 53.8% of their CD4 CTLs. Comparing the receptor sequences of the dominant CD4 CTL clones with a public database yielded matches from individuals diagnosed with lung, breast, and liver cancers, despite none of the study’s centenarians or supercentenarians having such diagnoses. This finding led researchers to propose that the expansion of CD4 CTLs could reflect early immune responses to abnormal or potentially cancer-related targets. However, the study does not establish a direct causal link between high levels of CD4 CTLs and protection against cancer or increased longevity, as the specific targets and behaviors of these cells outside the bloodstream remain unknown. Source

This is a summary. Read the original at sciencedaily.com.