title: Thymic epithelial cells of human patients affected by myasthenia gravis overexpress IGF-I immunoreactivity.
abstract: Accumulating evidence shows that several kinds of thymic cells express insulin-like growth factor-I (IGF-I), which is known to play an important role in T cell ontogeny under both physiological and pathological conditions. Still, little is known about the mechanisms of IGF-I involvement in the pathological transformation of the thymocyte microenvironment. The present study focuses on a comparative analysis of the IGF-I immunoreactivity of thymic epithelial cells (EC) from human patients with hyperplasia-associated myasthenia gravis (MG) versus physiological thymic tissue from healthy controls using immunohistochemistry and immunoelectron microscopy. We show that myasthenic EC overexpress IGF-I in comparison to EC from control subjects. The IGF-I immunoreactivity in the medullary and cortical EC from MG patients was stronger than in the normal gland. The increased expression of IGF-I and more frequent distribution of IGF-I and IGF-I-receptor (IGF-IR) immunopositive EC correlated with modulation in the immunoreactivity of double (IGF-I/IGF-IR) positive EC. Our data provide new immunocytochemial evidence for alterations of IGF-I and IGF-IR immunoreactivity in EC from pathological thymi. The persisting expression of IGF-I and IGF-IR most likely indicates that the myasthenic thymus is still capable of governing IGF-I signaling pathways, which are involved in the local regulation of T cell development and plasticity.
authors.affiliation: Department of Biology, Medical University Sofia, Bulgaria. tsvetamarin@yahoo.com
authors.forename: Tsvetana T
authors.initials: TT
authors.lastname: Marinova
authors.forename: Stefanie
authors.initials: S
authors.lastname: Kuerten
authors.forename: Danail B
authors.initials: DB
authors.lastname: Petrov
authors.forename: Doychin N
authors.initials: DN
authors.lastname: Angelov
mesh_terms: D000293:Adolescent; D000328:Adult; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D006965:Hyperplasia; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D009157:Myasthenia Gravis / Q000378:metabolism*; D013950:Thymus Gland / Q000378:metabolism* / Q000473:pathology*
chemical_list: D007334:Insulin-Like Growth Factor I