Bovine Interleukin-36 Receptor Antagonist (IL-36Ra) is an anti-inflammatory cytokine that regulates IL-36–mediated immune responses in cattle (Bos taurus). IL-36Ra is a member of the IL-1 cytokine family and functions as a natural inhibitor of the IL-36 signaling pathway by binding to the IL-36 receptor (IL-36R, also known as IL1RL2) without activating it, thereby preventing proinflammatory cytokines such as IL-36α, IL-36β, and IL-36γ from initiating downstream signaling. Through this mechanism, bovine IL-36Ra suppresses activation of intracellular pathways including NF-κB and MAPK, helping to limit production of inflammatory mediators and regulate immune responses at epithelial barrier tissues such as the skin, respiratory tract, and gastrointestinal mucosa. In cattle, IL-36Ra contributes to maintaining immune homeostasis and controlling excessive inflammatory responses during infection or tissue injury. In cell culture, recombinant bovine IL-36Ra is commonly used to inhibit IL-36–induced inflammatory signaling in epithelial and immune cells, allowing researchers to study cytokine regulation, epithelial–immune interactions, and modulation of inflammatory pathways in vitro. Bovine IL-36Ra is also studied in veterinary immunology and translational research to better understand mechanisms of epithelial inflammation, host–pathogen interactions, and immune regulation relevant to livestock health and comparative inflammatory disease biology.