Supercentenarians have an abundance of cancer-killing immune cells
The human immune system has specialized cells called CD4 cytotoxic T lymphocytes (CD4 CTLs), which have been shown to kill tumor cells in some cancers. When a person gets sick, these cells multiply in a process called clonal expansion to help fight infection. In a study published in the journal Cell Reports on Aug. 19, researchers show that these immune cells also may play a role in healthy aging…
Supercentenarians, individuals who live to 110 years or older, exhibit a unique characteristic in their immune systems: an abundance of cancer-killing immune cells called CD4 cytotoxic T lymphocytes (CD4 CTLs). A study published in the journal Cell Reports reveals that these specialized immune cells expand and adapt in supercentenarians, potentially contributing to healthy aging and longevity.
Researchers from the University of Osaka in Japan analyzed blood samples from 28 adults, divided into three age groups: 70-99, 100-109, and 110 and older. They found that the proportion of CD4 CTLs increased with age, reaching a median of 17.6% in participants over 110 years old. This expansion was not unique to centenarians and supercentenarians; even younger individuals had elevated levels of these immune cells.
The study revealed that the most prominent clone of CD4 CTLs accounted for an average of 33.3% of the total CD4 CTLs in the blood samples. In one centenarian's blood sample, a single clone made up an astonishing 53.8% of the CD4 CTL population. This clonal expansion suggests that older adults may be responding to persistent immune threats, such as cancer.
Interestingly, the researchers matched the receptor sequences of the most abundant CD4 CTL clones to a public database and found nearly three dozen matches with cancer-related targets, primarily lung, breast, and liver cancers. Despite the absence of any cancer diagnoses in the centenarians or supercentenarians studied, the researchers theorize that their CD4 CTL expansion may reflect early immune responses to these cancer-related targets.
While the study does not prove that having an abundance of CD4 CTLs prevents cancer or directly causes longer lifespan, it provides valuable insights into the adaptive capabilities of the immune system in extreme old age. The researchers plan to further investigate how these immune cells function within human tissues to better understand their role in healthy aging and longevity.
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