Common vampire bat 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 the common vampire bat (Desmodus rotundus). IL-22 is produced primarily by Th17 and Th22 CD4⁺ T cells, 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 production of antimicrobial peptides, promote epithelial cell proliferation, and enhance tissue repair. In healthy vampire bats, basal IL-22 expression is expected to be low but increases during bacterial or fungal exposure and mucosal immune challenge. Given that Desmodus rotundus is a natural reservoir for rabies virus and other zoonotic pathogens, IL-22 is of particular interest for understanding how bats maintain mucosal barrier integrity while tolerating persistent viral exposure with limited pathology. Study of common vampire bat IL-22 provides insight into epithelial immune regulation, host–pathogen balance, and the unique immune adaptations that characterize bat species.