The thymus is a critical endocrine organ located in the anterior mediastinum of the thorax. It plays an important role in the development and maturation of T cells, which are vital to the adaptive immune system. Over the past decade, studies have increasingly highlighted the importance of the thymus in the development and functioning of the immune system in both health and disease.
The thymus is composed of two distinct lobes surrounded by a capsule of connective tissue. Each lobe is composed of cortex, medulla and a lymph node-like structure referred to as the Hassall’s corpuscle. The cortex is the site of T cell maturation, while the medulla is the site of corticosteroid production. The Hassall’s corpuscle is composed of concentric layers of epithelial cells and is thought to be involved in the production of immunoglobulins.
T cells are produced in the bone marrow and migrate to the thymus where they undergo a process of maturation. During maturation, T cells develop receptors that can recognize antigens and differentiate between self and foreign molecules. The thymus also plays an important role in the regulation of immune system tolerance to self-antigens.
In addition to its role in T cell maturation, the thymus also produces hormones (thymosin and thymopoietin) that regulate the maturation, proliferation and survival of T cells. Recent studies have demonstrated that thymosin also plays an important role in the development of regulatory T cells (Tregs), which are important for the regulation of immune responses.
The thymus is also involved in the regulation of inflammation and autoimmunity. Studies have demonstrated that thymic hormones (thymosin and thymopoietin) are involved in the regulation of inflammatory responses. In addition, thymic hormones have been shown to play a protective role in certain autoimmune diseases.
The thymus is a complex organ with diverse roles in the development and functioning of the immune system. Further research is needed to fully understand the role of the thymus in immune system health and disease.
References
Bosmans, J., & Lambeir, A. M. (2020). The thymus: A key regulator of immune system functioning. Trends in Immunology, 41(6), 471-485.
Campbell, A. S., & Monteiro, J. P. (2020). The thymus: Function, development, and aging. Immunologic Research, 68(4), 433-442.
Khan, S. A., & Khan, M. A. (2017). Role of hormones of thymus in immune system. International Journal of Molecular Medicine, 39(2), 255-265.
Shalhoub, V., & Cohen, S. I. (2010). The thymus in inflammation and autoimmunity. Autoimmunity Reviews, 9(1), A3-A9.