Cynomolgus monkey IL-22 (Interleukin-22) is a member of the IL-10 cytokine family that plays a critical role in mucosal immunity and epithelial barrier protection in Cynomolgus monkeys (Macaca fascicularis). The IL-22 protein is highly conserved among non-human primates and closely homologous to that of Rhesus monkey and humans, supporting its strong translational relevance. IL-22 is produced primarily by activated CD4⁺ T cells, including Th17 and Th22 subsets, as well as by innate lymphoid cells (ILC3s), in response to microbial infection and inflammatory stimulation. It signals through the IL-22 receptor complex (IL-22R1 and IL-10R2), expressed mainly on epithelial and stromal cells, activating downstream JAK/STAT pathways—particularly STAT3—to induce antimicrobial peptide production, enhance chemokine expression, promote epithelial cell proliferation, and support tissue repair. In healthy Cynomolgus monkeys, basal IL-22 expression is generally low but increases during bacterial, viral, and inflammatory challenges, especially at mucosal surfaces of the respiratory and gastrointestinal tracts. In preclinical and translational research, Cynomolgus monkey IL-22 is particularly relevant in models of inflammatory bowel disease, respiratory infection, autoimmune disease, and biologic drug development, where it serves as a biomarker of mucosal immune activation and epithelial regenerative responses.