The Age-Associated Thymic Involution

The thymus gland is the heart of the immune system, especially during its development. It is the main site for the development of T lymphocytes. These cells are more often called T cells. T cells play a central and crucial role in the immune system. Thymus is the site where bone marrow derived very immature T cells are developed, so that mature and competent T cells can be produced and exported via circulation to the peripheral lymphoid tissues such as lymph nodes or spleen to play their active role in the immune system. (Picture from the National Cancer Institute)

The thymus shrinks gradually by age, a process called the “age-associated thymic involution”. This process starts normally after puberty. Thymic involution results is a decreased number of thymocytes or in other word immature T cells in the thymus. This leads to production of less mature T cells. Thymic involution may also involved in Immunosenescence, which refers to the gradual deterioration of the immune system especially in aged people. This might contribute to higher susceptibility of aged people to cancer and infection.