Cytokine that binds to and signals through the IL1RL1/ST2 receptor which in turn activates NF-kappa-B and MAPK signaling pathways in target cells. Involved in the maturation of Th2 cells inducing the secretion of T-helper type 2-associated cytokines. Also involved in activation of mast cells, basophils, eosinophils and natural killer cells. Acts as a chemoattractant for Th2 cells, and may function as an alarmin, that amplifies immune responses during tissue injury., In quiescent endothelia the uncleaved form is constitutively and abundantly expressed, and acts as a chromatin-associated nuclear factor with transcriptional repressor properties, it may sequester nuclear NF-kappaB/RELA, lowering expression of its targets. This form is rapidely lost upon angiogenic or proinflammatory activation. Biological Activity: Fully biologically active when compared to standard. The ED50 as determined by a cell proliferation assay using murine D10S cells is less than 0.5ng/ml, corresponding to a specific activity of > 2.0x10e6 IU/mg. Sequence: SIQGTSLLTQ SPASLSTYND QSVSFVLENG CYVINVDDSG KDQEQDQVLL RYYESPCPAS QSGDGVDGKK LMVNMSPIKD TDIWLHANDK DYSVELQRGD VSPPEQAFFV LHKKSSDFVS FECKNLPGTY IGVKDNQLAL VEEKDESCNN IMFKLSKI Molecular Weight: 17.5kD PubMed ID: 16286016, 16141072, 15489334, 19465481, 21734074, 22307629 Gene Name: Il33 Swiss Prot: Q8BVZ5 Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.