The roles of T helper 1, T helper 17 and regulatory T cells in the pathogenesis of sarcoidosis

Sarcoidosis is a systemic granulomatous disorder of unidentified etiology, with a heterogeneous clinical presentation. It is characterized by a reduced delayed- Type hypersensitivity to tuberculin and common antigens. The balance between Th1, Th17 and Regulatory T(Treg) cells controls T-cell proliferation and activation.The Th17/Treg ratio in the peripheral blood and bronchoalveolar lavage fluidis increased in patients with active sarcoidosis. Amplified IL-17A expression in granulomas and the presence of IL-17A+, IL-17A+IL-4+ and IL-17A+IFN-γ+ memory T helper cells in the circulation and BAL indicate Th17 cell involvement in granuloma induction and/or maintenance in sarcoidosis. Sarcoidosis should therefore be considered as a Th1/Th17 multisystem disorder and anti-IL-17/Th17 approaches that control and reduce IL-17Amay be an option, therefore, for the treatment of sarcoidosis.Here we provide a short overview as to the role of Th17 cells as critical cells in the pathogenesis of sarcoidosis.