CD194, also known as CCR4, is a CC chemokine receptor. It binds CCL17 and CCL22 and is expressed on a subset of T and B cells, basophils, monocytes, and NK cells. Human Th2 cells are characterized by the expression of CCR4 and CCR8, and these receptors are regulated differently during Th2 development. Human peripheral blood Tregs can be divided into two distinct populations based on the expression of CCR4. Freshly isolated Tregs express CCR4 and presumably represent memory-type Tregs, and CCR4^- Tregs require CD3-mediated activation to acquire a regulatory activity. Depletion of CCR4⁺ T cells leads to Th1-type polarization of CD4⁺ T cells and augmentation of CD8⁺ T cell responses to tumor antigens. CCR4 and its ligands are important for the recruitment of memory T cells into the skin in various cutaneous immune diseases.

Each lot of this antibody is quality control tested by immunofluorescent staining with flow cytometric analysis. For flow cytometric staining, the suggested use of this reagent is 5 microL per million cells or 5 microL per 100 microL of whole blood. It is recommended that the reagent be titrated for optimal performance for each application.