In the context of severe acute pancreatitis, which mediator is most closely linked to triggering systemic inflammatory response syndrome?

• A. TNF-α
• B. IL-4
• C. IL-10
• D. IFN-γ

Answer: (A)

In severe acute pancreatitis, tissue injury triggers an abrupt release of inflammatory mediators from injured tissue and activated immune cells. The cytokine that most closely triggers systemic inflammatory response syndrome is TNF-α. Released early by activated macrophages, TNF-α causes fever and rapid systemic effects such as widespread vasodilation and increased vascular permeability, leading to edema and hypotension. It also amplifies the inflammatory cascade by promoting other cytokines like IL-1 and IL-6, setting the stage for SIRS and potential organ dysfunction. While other cytokines have roles in immunity, they do not initiate the acute, systemic inflammatory surge in this scenario; IL-4 promotes humoral responses, IL-10 dampens inflammation, and IFN-γ, though proinflammatory, is not the primary trigger in pancreatitis-driven SIRS.