IL37 and neoplasm: IL-37 acts by forming a complex with IL-18Rα (IL-1R5) and IL-1R8 (SIGIRR), a reaction that is important for its anti-inflammatory signals, while IL-38 is a more complex molecule that often functions as an antagonist of IL-36 signaling (binding IL-36R and other receptors) and can promote tumor immunosuppression.