Aging of thymus gland and immune system

Aging is an inevitable, progressive and irreversible process that is manifested with multiple organ dysfunction. Reactive oxygen species (ROS) is considered the main etiological factor of aging. The thymus gland is the primary site of T cell production and it represents a key organ of the immune system. It is endodermal in origin and lies in the anterior mediastinum behind the sternum. Thymic involution with aging results in less efficient T-cell development and decreased emigration of naive T cells to the periphery. Deterioration of the immune system with aging contributes to increased incidence of infection, autoimmunity, and cancer, thus increasing the rates of morbidity and mortality in elderly humans.