IL 18 Signaling Pathway
IL-18 is a pro-inflammatory cytokine similar in structure and mechanism of action to IL-1 beta. Formation of active IL-18 by macrophages requires cleavage of an inactive precursor by caspase-1 protease, also termed the IL-1 converting enzyme (ICE). One of the key biological responses induced by IL-18 is that in combination with IL-12 it stimulates Th1 cell differentiation and involvement in immune responses. IL-18 was originally known as interferon-gamma-inducing factor, named after its induction of interferon-gamma production. Up-regulation of Fas ligand in Th1 cells by IL-18 may increase apoptosis of Fas receptor expressing cells that interact with the activated Th1 cells. This induction of apoptosis may allow IL-18 to have anti-tumor activity and may also play a role in chronic inflammatory and autoimmune conditions.
Contributor: Glenn Croston, PhD.
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