Dolphin CCL22 (C-C motif chemokine ligand 22, also known as macrophage-derived chemokine, MDC) is an immunoregulatory chemokine involved in recruitment of specific T cell populations during immune responses in dolphins, particularly the bottlenose dolphin (Tursiops truncatus). CCL22 primarily signals through the CCR4 receptor, promoting chemotaxis of Th2 cells, regulatory T cells (Tregs), and certain dendritic cell populations to sites of inflammation or immune activation. In dolphins, CCL22 is likely produced by macrophages, dendritic cells, and epithelial cells in response to inflammatory stimuli, helping regulate immune balance by directing lymphocyte trafficking and modulating inflammatory responses. In dolphin health, CCL22-mediated CCR4 signaling may play roles in chronic inflammatory conditions, respiratory infections, skin lesions, and wound healing, where regulation of T cell recruitment is important for controlling inflammation and promoting tissue repair. Dysregulated expression of CCL22 could contribute to altered immune regulation, potentially influencing chronic inflammation or immune tolerance during exposure to environmental stressors such as pollutants, harmful algal toxins, or infectious disease outbreaks. Because dolphins serve as sentinel species for marine ecosystem health, characterization of dolphin CCL22 supports research into immune regulation, environmental immunotoxicology, and host–pathogen interactions in marine mammals, providing comparative insight into chemokine-mediated immune balance across mammalian species.