Thymic physiology and pathophysiology in Myasthenia Gravis

The thymus is a central lymphoid organ responsible for T-cell development and maturation and is crucial in adaptive immunity. This organ creates a specialized environment for thymocyte differentiation and positive/negative selection, ensuring the survival of functional and self-tolerant T cells while eliminating autoreactive clones. This process, which is known as T-cell education, involves interactions between developing T cells and stromal cells, primarily thymic epithelial cells, which present tissue-specific antigens. Proper thymus function remains vital for maintaining immune homeostasis. However, thymic abnormalities have been implicated in Myasthenia Gravis (MG), where the thymus often exhibits lymphofollicular hyperplasia or thymomas, which may trigger an autoimmune response against the acetylcholine receptor at the neuromuscular junction. This leads to impaired neuromuscular transmission and characteristic muscle weakness. Understanding the etiological mechanisms underlying thymic alterations associated with MG is crucial for elucidating immune dysregulation resulting from an abnormal thymus, which may persist even post-therapeutic thymectomy.