What is the role of the thymus gland in myasthenia gravis?
The thymus gland, which lies in the upper chest area beneath the breastbone, plays an important role in the development of the immune system in early life. Its cells form a part of the body’s normal immune system. The gland is somewhat large in infants, grows gradually until puberty, and then gets smaller and is replaced by fat with age. In adults with myasthenia gravis, the thymus gland is abnormal. It contains certain clusters of immune cells indicative of lymphoid hyperplasia – a condition usually found only in the spleen and lymph nodes during an active immune response. Some individuals with myasthenia gravis develop thymomas or tumors of the thymus gland. Generally thymomas are benign, but they can become malignant. The relationship between the thymus gland and myasthenia gravis is not yet fully understood. Scientists believe the thymus gland may give incorrect instructions to developing immune cells, ultimately resulting in autoimmunity and the production of the acetylcholine rec