A recombinant partial protein (within amino acids 1-193) from the human protein was used as the immunogen for the IL-18 antibody.
Four structurally related IL-1 receptor ligands have been described. These include three agonists designated IL-1Alpha, IL-1beta and IL-1gamma/IL-18 and a specific receptor antagonist, IL-1RAlpha. IL-1Alpha and IL-1beta play critical roles in the regulation of the immune response and inflammation, serving as activators of T and B lymphocytes and NK (natural killer) cells. IL-18 (also referred to as IL-1gamma) has been shown to augment the secretion of IFN-gamma from T lymphocytes and increase NK cell activity in spleen cells. IL-18 exhibits 19% and 12% identity with IL-1Alpha and IL-1beta respectively over the 12 beta-strands of the beta-trefoil fold domain, which is a signature feature of the IL-1 family. The unusual leader sequence of IL-18 may be analogous to the IL-1beta pro-domain which must be cleaved by the serine protease ICE for optimal secretion and biological activity. Originally described as IGIF (IFN-gamma-inducing factor), IL-18 is induced by mouse liver subsequent to challenge with lipopolysaccharide (LPS).
