Rhesus macaque Interleukin-18 (rMamu IL-18)
IL-18 or IFN- inducing factor shares many activities exerted by IL-12 including the stimulation and expansion of NK cells, promotion of Th-1 T cell responses, and promotion of acute inflammatory responses following LPS exposure. The pathway of activation of IL-12 and IL-18 is however not redundant but rather synergistic as IL-12 has been found to up-regulated IL-18-receptor expression. IL-18 is produced by a variety of tissues, including liver macrophages, pancreas, PBMCs, skeletal muscle, kidney, etc.
rMamu IL-18 cDNA code for a 193 aa precursor protein (resulting in a 157 aa mature polypeptide) that is 97.4% homologous to human IL-18. Unpublished data from our laboratory suggests that while biologically active in vitro, this mature molecule produced without its actual caspase mediated processing or produced via fusion with another leader peptide to show little IFN- induction in monkeys in vivo, suggesting some critical maturation step during natural cleavage.
rMamu IL-18 is produced as a mature polypeptide in E coli using the pET32 expression vector with an enterokinase digestion site to ensure the absence of extraneous residues at the aminoterminus.
Purity is verified by PAGE electrophoresis and absence of endotoxin by LAL test.
Bioactivity of each lot is tested based on induction of IFN- production and proliferation in PBMC stimulated with suboptimal doses of IL-12.