IL-33 is a member of the interleukin family of cytokines that regulates a wide variety of cellular functions. Its receptor is ST2, an IL-1 receptor family member that also acts as a negative regulator of TLR-IL-1R signaling and the IL-1R accessory protein (IL-1RAcP). Receptor binding of IL-33 activates NF-kB and MAP kinases, stimulating downstream expression of TH2-associated cytokines such as IL-4, IL-5 and IL-6.
