IL21 and Autoimmunity: Conversely, anti-inflammatory cytokines such as IL-10, Interleukin-4 (IL-4), Interleukin-13 (IL-13), and Interleukin-21 (IL-21) help mitigate tissue damage and prevent autoimmunity, yet their overexpression in critically ill patients has been linked to immune exhaustion or “immunoparalysis”, which predisposes individuals to secondary infections and increased mortality [39,43,44,45,46].