IL21 and Autoimmunity: Th17 cells mainly participate in and promote the occurrence and development of autoimmunity, while secreting many pro-inflammatory cytokines, including IL-17, TNF-α, INF-γ, IL-1β, IL-6, IL-8, IL-21, IL-22, GM-CSF, as well as adhesion molecules ICAM-1, VCAM-1, which can induce and amplify inflammation (Bsat et al., 2019).