The CCL1 (C-C motif chemokine ligand 1) gene, located on the q-arm of chromosome 17, encodes a small glycoprotein (approximately 15-16 kDa) belonging to the CC chemokine family. This protein, also known as I-309, is primarily expressed by activated T cells, monocytes/macrophages, and endothelial cells ^[1]. Its main function is as a chemoattractant, specifically drawing monocytes/macrophages, T lymphocytes (especially Th2-differentiated T cells and regulatory T cells), and some dendritic cells to sites of inflammation and immune responses. CCL1 exerts its effects by binding to the chemokine (C-C motif) receptor 8 (CCR8), which is found on various immune cells ^[2]. Beyond its role in immune cell trafficking, CCL1 has antimicrobial activity against bacteria like E. coli and S. aureus, and it can inhibit apoptosis in certain cell lines via the RAS/MAPK pathway ^[3]. CCL1 is implicated in various inflammatory and immune-related disorders, including asthma, atopic dermatitis, rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), tuberculosis, and certain cancers like breast cancer, cervical cancer, and Kaposi Sarcoma, where its dysregulation can contribute to disease pathogenesis ^[3-4]. Cellular tissues where CCL1 expression is notable include the thymus, muscle, stomach, and various immune cells such as T cells, monocytes, B cells, and endothelial cells ^[4].

The B6-hCCL1 mouse is a humanized model, constructed by replacing the coding sequences of the endogenous mouse Ccl1 gene with the coding sequences of the human CCL1 gene. B6-hCCL1 mice can be used for research into the pathogenesis of various inflammatory and immune-related disorders, including asthma, atopic dermatitis, rheumatoid arthritis (RA), chronic obstructive pulmonary disease (COPD), tuberculosis, and certain cancers like breast cancer, cervical cancer, and Kaposi Sarcoma, as well as for the development of CCL1-targeted drugs.