A chemokine receptor binds to MCP-1, MIP-1.alpha. and/or RANTES. It can be used in screening for agents which act as antagonists to MCP-1, MIP-1.alpha. and/or RANTES. Such agents may be useful in treating various disorders, including allergies, atheromas and diseases mediated by viruses. They may also be useful in preventing graft rejection and in protecting stem cells from potentially damaging effects of chemotherapy.