Role of Th17 cells and IL-17, IL-23 cytokines in pathogenesis of autoimmune thyroid disease in children

Introduction Up till now, altered balance of Th1 and Th2 immune cells has been postulated to play an important role in the pathogenesis of autoimmune thyroid diseases (AITD). However, recent studies on thyroid diseases suggest a new role for Th17 (T helper 17) cells that have been classified as a new lineage, distinct from Th1, Th2 and Treg cells. Despite wide interest, the role of Th17 cells in the pathogenesis of inflammatory and autoimmune diseases is still being debated. Th17 cells are involved in immune responses against extracellular pathogens and have the ability to secrete cytokines: IL-17, IL-17F, IL-21 and IL-23. Th17 cells can be characterized by several surface markers, i.e. CCR6 (CD196), IL-23R, IL-12Rbeta2 and CD161.