CCR3 (C-C chemokine receptor type 3 or eosinophil eotaxin receptor) is a receptor for a C-C type chemokine and binds to eotaxin, eotaxin-3, MCP-3, MCP-4, RANTES and MIP-1 delta. The receptor subsequently transduces a signal by increasing the intracellular calcium level. Similar to CCR2, it is another alternative coreceptor with CD4 for HIV-1 infection. CCR3 is expressed on eosinophils, basophils, mast cell subpopulations, activated Th2 cells, macrophages and airway epithelial cells. Hence, CCR3 is closely associated with asthma and allergy and blockade of this receptor may have pronounced beneficial effects in these diseases.