CD198, also known as C-C chemokine receptor type 8 （CCR8）, is a 41 kD G protein-coupled receptor with seven transmembrane regions, belonging to the beta chemokine receptor family. It is expressed by various immune cells, including subsets of thymocytes, Tregs, NKT cells, Th2-polarized cells, macrophages, monocytes, and monocyte-derived dendritic cells. CCR8 plays a role in mediating chemotaxis toward its ligands, such as CCL1 and CCL18, and is involved in the regulation of monocyte chemotaxis and thymic cell apoptosis. Additionally, CCR8 is associated with Th2 lymphocytes and has a role in allergic diseases. It is also considered an alternative coreceptor to CD4 for HIV-1 infection.