CCL15 (C-C motif chemokine ligand 15), also known as MIP-1gamma, is a CC chemokine that functions primarily as a chemoattractant for T cells and monocytes 1. It acts mainly through CC chemokine receptor CCR1 and also binds CCR3, with proteolytically processed forms (CCL15(22-92), CCL15(25-92), CCL15(29-92)) demonstrating enhanced potency as chemoattractants. Mechanistically, CCL15 mediates immune cell recruitment and activation through CCR1-dependent signaling pathways. In allergic airway inflammation, the CCL6-CCR1 axis (human ortholog CCL15) promotes eosinophil differentiation and airway inflammation, with CCR1 antagonists effectively reducing disease severity 2. In intestinal fibrosis, MDSC-derived CCL15 activates fibroblasts via CCR1-MAPK signaling 3. CCL15 exhibits complex roles in cancer immunology. In hepatocellular carcinoma, CCL15 expression in the tumor core facilitates immunosuppression by recruiting and polarizing M2-like macrophages, with elevated CCL15 predicting poor prognosis 4. Conversely, CCL15 produced by liver cancer cells drives polarization of macrophages toward pro-tumoral SPP1+ phenotypes, establishing a tumor-promoting feedback loop 5. Circulating CCL15 associates with heart failure development, suggesting systemic inflammatory involvement 6. These findings identify CCL15-CCR1 pathway modulation as a potential therapeutic target for inflammatory diseases, fibrosis, and cancer.