T cells of the adaptive immune system collectively become less functional with age. The immune system as a whole becomes more inflammatory and less effectively, a state described by the terms inflammaging and immunosenescence. Researchers here note that T cells struggle to survive in the aged environment, and are as a consequence metabolically inefficient. Their efforts are going towards survival rather than the activities of immune surveillance. The degree to which this contributes to immunosenesence versus other factors is an open question.
In a recent study, researchers outline that the increased metabolism of T cells observed with advanced age was an indication that they were working harder merely to survive. This contradicts previous knowledge, which suggested an increased metabolism was indicative of T cell function, and will have implications for the development of targeted interventions such as vaccines or immunotherapies to treat age-related immune dysfunction.
T cells play an important role in the body's immune response to viral infections and tumors, but T cell immunity wanes as we age, thus increasing our susceptibility to these diseases. "We've shown that an amped-up metabolism, rather than arming cells to fight pathogens better, is associated with T cell survival over a lifespan. The cells need to substantially increase their metabolism just to survive in the relatively hostile environment of the elderly. This work is important because one of the hallmarks of immune aging is the loss of T cells. Ultimately we want to support healthy ageing by designing ways to improve T cell metabolism during cell-based immunotherapies such as CAR T cell therapy, and boosting T cell activation in new vaccines.