Recombinant human IL-18 protein (Qk100)

Protein background

Interleukin-18 (IL-18) is a pro-inflammatory cytokine belonging to the IL-1 family, produced by macrophages and dendritic cells. It plays a central role in both innate and adaptive immunity, particularly in antiviral defense. IL-18 stimulations interferon-gamma (IFN-γ) production by natural killer (NK) cells and CD4+ T-cells, which enhances immune responses against intracellular pathogens such as viruses and bacteria [1].

IL-18 is synthesized as an inactive precursor and activated by caspase-1 cleavage. The mature protein, approximately 18 kDa in size, has a β-trefoil fold and interacts with its receptor (IL-18R) to trigger immune signaling pathways such as NF-κB and MAPK [1].

IL-18 works with IL-12 to promote the differentiation of Th1 cells, contributing to a robust cell-mediated immune response. It also induces the production of other inflammatory cytokines, including TNF-α, and promotes the migration of immune cells to sites of infection or injury by increasing the expression of adhesion molecules. IL-18 plays a role in autoimmune disease, such as rheumatoid arthritis and inflammatory bowel disease, where excessive IL-18 activity contributes to inflammation and tissue damage. Recent research has suggested that IL-18 also has metabolic functions, influencing insulin sensitivity and lipid metabolism. Deficiency in IL-18 is linked to a higher risk of metabolic disorders, including obesity and type 2 diabetes [2,3].

IL-18 is a target for therapeutic applications in autoimmune diseases, where blocking its activity may reduce inflammation. In cancer immunotherapy, IL-18’s role in stimulating NK cell and T-cell responses is being explored to enhance the immune system’s ability to target tumors. Additionally, it is being studied as an adjuvant in vaccines and potential treatments for viral infections like HIV and hepatitis C, due to its ability to amplify immune responses [4].