Chicken CCL1 (C-C motif chemokine ligand 1) is a member of the CC chemokine family that participates in regulating leukocyte trafficking and immune responses in chickens (Gallus gallus). CCL1 is expressed primarily by activated T lymphocytes, monocytes/macrophages, and certain epithelial or stromal cells in response to inflammatory cytokines and microbial stimulation, and it functions through a CCR8-like receptor to promote recruitment and activation of T cells and other immune effector cells at sites of infection or tissue injury. In healthy chickens, basal CCL1 expression is typically low but increases during immune activation. Upregulation has been observed in response to viral and bacterial infections, including infectious bursal disease virus (IBDV), Marek’s disease virus (MDV), avian influenza virus, and enteric pathogens, as well as during vaccination and inflammatory challenge. In poultry science and avian immunology research, chicken CCL1 serves as a biomarker of cellular immune activation and Th-type responses, providing insight into leukocyte migration, host–pathogen interactions, and immune regulation in commercial and experimental poultry systems.