CD194, also known as CC chemokine receptor 4 (CCR4), belongs to the G protein-coupled receptor family. It is expressed on stimulated and unstimulated T and B cells, basophils, monocytes and NK cells. Human peripheral blood regulatory T cells (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 anti-CD3 antibody-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.
Anti-Human CD194/CCR4 (L291H4)-158Gd—50 Tests