Thymic Epithelial Cells (TEC)

Thymic epithelial cells (TEC), which express MHC molecules, mediate positive selection. Thymocytes will undergo positive selection when they express a TCR, which can bind with low avidity to self-class I or class II (MHC). Thymocyte maturation requires the participation of thymic epithelial cells and extracellular matrix components.Thymic epithelial cells synthesize galectin-1, can induce apoptosis of T cells and can mediate negative selection. Findings show that galectin-1, a beta-galactoside binding protein, is produced by thymic epithelial cells and binds to human thymocytes.Studies have shown that changes in the expression of tumor necrosis factor receptor family members and transcription factors Foxn1 and autoimmune regulator (Aire) can alter the thymic microenvironment and self-tolerance.