Dolphin CCL5 (C–C motif chemokine ligand 5, also known as RANTES – Regulated upon Activation, Normal T cell Expressed and Secreted) is a proinflammatory chemokine that regulates immune cell recruitment and inflammatory responses in dolphins, particularly the bottlenose dolphin (Tursiops truncatus). CCL5 is a member of the CC chemokine family, which also includes CCL3 (MIP-1α), CCL4 (MIP-1β), and CCL2 (MCP-1), chemokines that coordinate leukocyte trafficking during immune activation. In dolphins, CCL5 is produced primarily by activated T lymphocytes, macrophages, dendritic cells, platelets, and epithelial cells in response to infection, inflammatory stimuli, or tissue injury, and exerts its biological effects mainly through binding to the chemokine receptors CCR1, CCR3, and CCR5, promoting chemotaxis and activation of T cells, monocytes/macrophages, eosinophils, and natural killer (NK) cells at sites of inflammation. Through these actions, dolphin CCL5 contributes to immune defense against viral, bacterial, and parasitic pathogens encountered in marine environments. Because dolphins are considered sentinel species for ocean health, studying chemokines such as CCL5 helps improve understanding of marine mammal immunology, host responses to infectious disease, and the effects of environmental stressors or pollutants on immune function.