IL 33 Human, His

Interleukin-33 (IL-33) is a cytokine belonging to the IL-1 family, known for its role in immune response modulation. The recombinant form of IL-33, tagged with a histidine (His) tag, is widely used in research to study its biological functions and interactions.

IL-33 is a 32 kDa proinflammatory cytokine composed of 169 amino acid residues . It is primarily expressed in endothelial cells, epithelial cells, fibroblasts, and mesenchymal cells . The recombinant IL-33 is often produced in Escherichia coli expression systems and tagged with a His tag at the C-terminus to facilitate purification and detection .

IL-33 plays a crucial role in the immune system by binding to its receptor, ST2 (IL1RL1), and activating downstream signaling pathways such as NF-κB and MAPK . This activation leads to the production of type 2 cytokines, including IL-5 and IL-13, which are essential for allergic inflammation and immune response .

Upon binding to the ST2 receptor, IL-33 activates various immune cells, including mast cells, basophils, eosinophils, and natural killer cells . It acts as a chemoattractant for Th2 cells and may function as an “alarmin,” amplifying immune responses during tissue injury . Proteolytic processing by enzymes such as cathepsin G and neutrophil elastase produces more active C-terminal peptides .

Recombinant IL-33 with a His tag is used in various research applications, including:

• sELISA (sandwich ELISA): To quantify IL-33 levels in biological samples .
• SDS-PAGE: To analyze the purity and molecular weight of IL-33 .
• Functional assays: To study the biological activity of IL-33 in inducing cytokine production and cell proliferation .

The recombinant IL-33 protein is typically lyophilized and stored at -20°C or lower for long-term stability . Upon reconstitution, it should be stored under sterile conditions to prevent degradation and maintain its biological activity .