Antigen-specific T-cell activation in hyperplastic thymus in myasthenia gravis

• Published in: Muscle & nerve 2007-07, Vol.36 (1), p.100-103
• Main Authors: Utsugisawa, Kimiaki, Nagane, Yuriko, Suzuki, Shigeaki, Kondoh, Ryushi
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Antigens, CD - metabolism; Biological and medical sciences; CD83 Antigen; dendritic cell; Diseases of striated muscles. Neuromuscular diseases; Female; Fundamental and applied biological sciences. Psychology; Gene Expression - immunology; Humans; Hyaluronan Receptors - metabolism; Immunoglobulins - metabolism; Male; Medical sciences; Membrane Glycoproteins - metabolism; Middle Aged; myasthenia gravis; Myasthenia Gravis - complications; Myasthenia Gravis - immunology; Myasthenia Gravis - pathology; Neurology; Protein Kinase C - metabolism; protein kinase Cθ; Striated muscle. Tendons; T cell activation; T-Lymphocytes - cytology; T-Lymphocytes - immunology; T-Lymphocytes - metabolism; Thymectomy; thymus; Thymus Hyperplasia - etiology; Thymus Hyperplasia - immunology; Thymus Hyperplasia - pathology; Thymus Hyperplasia - surgery; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 0148-639X; 1097-4598
• DOI: 10.1002/mus.20794

In order to determine whether antigen‐specific T‐cell activation by dendritic cells (DCs) is accelerated in thymuses exhibiting lymphofollicular hyperplasia (TLFH) among patients with early‐onset myasthenia gravis (EOMG), we investigated the expression levels of phosphorylated protein kinase C (PKC)θ and the local relationship between the presence of phosphorylated PKCθ and the homing receptor CD44 or CD83, a marker for mature DCs, in samples taken from EOMG patients with early improvement following thymectomy, in remnant thymuses from late‐onset MG patients, and in non‐MG control thymuses. Antigen‐specific T‐cell activation was markedly accelerated in TLFH from EOMG patients. Activated T cells and adjacent DCs appeared to be components of a CD44high cell population circulating from the blood to the thymus. Although there is no convincing evidence that thymectomy is of benefit in MG, in some EOMG patients with early improvement following thymectomy, blockade of CD44‐associated circulation mechanisms is probably the cause for the early benefits of thymectomy and is a potential alternative to thymectomy. Muscle Nerve, 2007