Human Chemokine C-C-Motif Receptor 4 (CCR4) Protein

Background

C-C Chemokine Receptor Type 4 (CCR4) is a G-protein-coupled receptor (GPCR) primarily expressed on T-helper 2 (Th2) lymphocytes, regulatory T cells (Tregs), natural killer (NK) cells, and dendritic cells. CCR4 selectively binds chemokines like CCL17 (TARC) and CCL22 (MDC), mediating immune cell migration, trafficking, and activation. It plays a significant role in directing T-cell responses during allergic inflammation and immune homeostasis. CCR4 facilitates the recruitment of Th2 cells to tissues such as the lungs, skin, and mucosal surfaces, making it a critical mediator in conditions like asthma, atopic dermatitis, and allergic rhinitis. Additionally, CCR4 is highly expressed on regulatory T cells (Tregs), which suppress immune responses and maintain tolerance, particularly in tumors, where Tregs suppress anti-tumor immunity. Elevated CCR4 expression is associated with T-cell lymphomas, including adult T-cell leukemia/lymphoma (ATLL) and cutaneous T-cell lymphoma (CTCL), where it contributes to tumor progression and immune escape. CCR4 has emerged as a therapeutic target for both autoimmune diseases and cancer. Antibodies and small-molecule antagonists targeting CCR4 are being explored to inhibit Treg recruitment in tumors, restore anti-tumor immunity, and reduce inflammation in allergic diseases. Understanding the complex interplay of CCR4 in immune responses continues to drive its role as a therapeutic target in immunotherapy and inflammatory diseases.