Dolphin IL-22 (Interleukin-22) is a member of the IL-10 cytokine family that plays an important role in mucosal immunity and epithelial barrier protection in dolphins (e.g., Tursiops truncatus). IL-22 is produced primarily by activated CD4⁺ T cells, including Th17- and Th22-like populations, as well as by innate lymphoid cells 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 dolphins, basal IL-22 expression is expected to be low but increases during bacterial, viral, or fungal infections and during inflammatory challenges affecting respiratory, gastrointestinal, or dermal tissues. In marine mammal and comparative immunology research, dolphin IL-22 is of interest for understanding mucosal defense mechanisms, host responses to environmental stressors and pathogens, and the maintenance of epithelial integrity in both managed and free-ranging populations.