Human Interleukin 33, IL-33 ELI

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 (PubMed: 16286016).

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 (PubMed: 17853410, PubMed: 18836528).

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 (PubMed: 21734074).

This form is rapidely lost upon angiogenic or proinflammatory activation (PubMed: 18787100).