Cynomolgus Monkey (Macaca fascicularis) Tumor Necrosis Factor Alpha (TNF-α) (also known as TNF or cachectin) is a proinflammatory cytokine that plays a central role in innate immune responses, inflammation, and host defense against pathogens in nonhuman primates. TNF-α is a member of the tumor necrosis factor (TNF) superfamily, which includes related cytokines such as TNF-β (lymphotoxin-α), Fas ligand (FasL), CD40 ligand (CD40L), and TRAIL, molecules involved in immune signaling, apoptosis, and inflammatory regulation. In cynomolgus monkeys, TNF-α is primarily produced by activated macrophages, monocytes, dendritic cells, and T lymphocytes in response to infection, endotoxin exposure, or tissue injury. TNF-α exerts its biological effects by binding to TNF receptors TNFR1 (p55) and TNFR2 (p75), activating intracellular signaling pathways including NF-κB, MAPK, and caspase-mediated pathways, which regulate cytokine production, immune cell activation, apoptosis, and inflammatory responses. Because cynomolgus monkeys are widely used as preclinical models for human infectious diseases, immunology, and inflammatory disorders, TNF-α has been extensively studied in models of tuberculosis, viral infections, autoimmune disease, and sepsis, where dysregulated TNF signaling contributes to inflammation, tissue damage, and immune-mediated pathology. Due to their close genetic and immunological similarity to humans, characterization of cynomolgus monkey TNF-α is important for translational research and evaluation of anti-TNF therapies and other immunomodulatory treatments prior to clinical development.