Mouse CCL22 (C-C motif chemokine ligand 22, also known as macrophage-derived chemokine, MDC) is an immunoregulatory chemokine that plays an important role in directing T cell trafficking and modulating immune responses in mice (Mus musculus). CCL22 primarily signals through the CCR4 receptor, promoting chemotaxis of Th2 cells, regulatory T cells (Tregs), and certain dendritic cell populations to sites of immune activation or inflammation. In mice, CCL22 is produced mainly by macrophages, dendritic cells, and epithelial cells following stimulation by inflammatory cytokines or pathogen-associated signals. CCL22-mediated CCR4 signaling contributes to regulation of immune balance by promoting recruitment of T cells involved in allergic responses, immune tolerance, and resolution of inflammation. In murine research, CCL22 is widely studied in experimental models of allergic airway disease (asthma), atopic dermatitis, autoimmune disorders, and tumor immunology, where it influences recruitment of regulatory T cells and Th2 cells to inflamed tissues or tumor microenvironments. While CCL22-driven immune cell trafficking helps regulate immune responses and maintain tolerance, excessive expression can contribute to chronic inflammation or immune suppression within tumors. Because mice are the primary genetic model for studying immune regulation, characterization of mouse CCL22 has been essential for understanding CCR4-mediated T cell migration, allergic inflammation, and tumor immune evasion, providing insights relevant to human immunology and therapeutic development.