Description: Mouse IL-33, also called NF-HEV and DVS 27, is a 30 kDa proinflammatory cytokine produced by endothelial and epithelial cells. IL-33 is released during necrotic cell death but was first found in the nucleus of endothelial cells. This dual pattern of expression is reminiscent of "alarmins" also known as endogeneous danger signals. Other known alarmins are IL-1 alpha; and HMGB1. IL-33 has been identified as the ligand for ST2 (a member of the Il-1 receptor family). ST2 is stably expressed on mast cells and T(h)2 effector T cells and is functionally associated with T(h)2-mediated inflammation. Although IL-33 was initially reported to be processed by Caspase-1, recent data indicate that Caspase-3 or -7 are capable of processing IL-33 at more physiologic concentrations. IL-33 plays an immune regulatory role by inducing IL-5 and IL-13 in vitro and in vivo and activating basophils, eosinophils and mast cells. In addition to its role in proimflammation, it may also decrease inflammation through interactions with IL-1 thereby blocking its effect. Mouse IL-33 share 55% amino acid sequence identity with human and 90% with rat.