Abstract
Aging is a universal and complex process that affects all tissues and cells types, including immune cells, in a process known as immunosenescence. However, many aspects of immunosenescence are not completely understood, as the characteristics of the immune cells of nonagenarians and centenarians or the features and implications of extracellular vesicles (EVs). In this study, we analyzed blood samples from 51 individuals aged 20-49 and 70-104 years. We found that senescent CD8 cells accumulate with age, while there is a partial reduction of senescent CD4 cells in nonagenarians and centenarians. Moreover, plasma EVs carry T cell specific markers, but no accumulation of "senescent-like EVs" was found within any of analyzed age groups. Our functional studies of cocultures of peripheral blood mononuclear cells and EVs showed that EVs enhance T cell viability and, under phytohemagglutinin stimulation, they influence cytokine secretion and cell activation in an age-dependent manner. These results underline the importance of EVs on the immune system functioning, and open new perspectives to further study their implication in human aging.