Supercentenarians – people who live to be 110 years of age or older – have long healthspans, free of disease and the physical and cognitive decline that commonly accompany aging. A critical factor in their long, healthy lives is a robust immune system. Findings from a new study reveal that supercentenarians have high levels of cytotoxic CD4 T-cells, a specialized type of white blood cell.

CD4 T-cells are key elements in the body’s antigen-specific immune response. They destroy virus-infected and malignant cells by triggering apoptosis – a type of cellular self-destruct mechanism that rids the body of damaged or aged cells. CD4 T-cells are considered “helper” cells in that they assist other cells in the immune response.

The authors of the study collected circulating immune cells in the blood of seven supercentenarians and five controls, who were between the ages of 50 and 80 years. They found that the supercentenarians had considerably higher levels of CD4 T-cells than the controls, and these CD4 T-cells had unique cytotoxic capabilities. Furthermore, they found that the cytotoxic cells had arisen via clonal expansion, the process by which daughter cells arise from a single parent cell.

Cytotoxic CD4 T-cells are rare, even among young people, but they play key roles in immunosurveillance and can kill cancer cells. These findings shed light on how supercentenarians maintain good health throughout their lives.

• Link to full study.