Exosome research has seen breakthrough in the past years: several physiological changes (development, aging) and diseases (inflammation, cancer) have been linked to exosomes. The thymic epithelium is an unusually rich source of exosomes compared to other tissues. Also their special characteristics (lack of surface CD63 molecule) allow for their specific enrichment from human serum samples. Thymocytes develop in the thymus to become naive T-cells of the peripheral blood once fully mature where they provide protection from infection and cancer. So-called regulatory T-cells that regulate autoimmune disorders also develop in the thymus. With age the incidence of infections, cancer and autoimmune disorders increases. Our research aims to determine changes in miRNA profile of human thymic epithelial exosomes with age and to clarify their role in the development of infections, cancer and autoimmune disorders.