Interleukin 36 receptor antagonist (IL-36RA) is a 17.21 kDa cytokine with 155 amino acid residues and a member of the IL-36 family. It is mainly secreted from the stomach, lungs, and kidneys. IL-36RA binds to the interleukin-36 receptor and plays a critical role in the anti-inflammatory effect by mediating MAPK and NF-κB signaling pathways. IL-36RA inhibits proinflammatory effect via suppressing production of IL-6, IL-17, and interferon-gamma and promoting production of IL-4.