Invitrogen™ Human ST2 (IL-33R) ELISA Kit

IL-33R, also known as ST2, is a receptor for IL-33. It is a member of the IL-1 receptor family of innate receptors. Its extracellular domain consists of 3 Ig-like domains that directly interact with its co-receptor IL-1RAcP, and the ligand alarmin, IL-33. IL-33 ligation results in the association of IL-33R complex with its adaptor proteins MyD88, IRAK1, IRAK4 and TRAF6, and activation of the NF-kB, and MAPK pathways. This, in turn, instigates the release of chemokines and cytokines such as IL-5, IL-6, IL-8, and IL-13. Two most common isoforms of IL-33R that result from alternative splicing are ST2L - the membrane bound form, and ST2S - the soluble form. The membrane bound form can be released from the cell surface by proteolytic cleavage. The soluble forms have been suggested to act as decoys dampening the IL-33 signaling. IL-33R is primarily expressed by mast cells, basophils, and eosinophils. In mouse, IL-33R expression has been shown on ILC2 and Th2 cells. IL-33R signaling has been implicated in the number of immune conditions, including allergies, arthritis, atherosclerosis and sepsis.