IL17A and autoimmune disease: Viral, bacterial, neoplastic, and autoimmune diseases – as well as immune-modifying drugs – are believed to play a role in its pathogenesis.1, 2, 3 The T-helper 1 (Th1) immune response pathway is activated, with increased proinflammatory cytokines such as tumor necrosis factor-α, interferon-α, interleukin-1, interleukin-6, interleukin-17, and interleukin-23.4