Monocyte chemotactic protein MCP-2 is a C-C chemokine. It shares over 60% amino acid identity with MCP-1 and MCP- 3 and has about 30% identity with other C-C chemokines MIP-1 alpha, RANTES, and MIP-1 beta. MCP-2 is chemotactic for and activates a wide variety of inflammatory cells, and its spectrum of action on leukocytes is similar to that of MCP-3, including monocytes, T lymphocytes, natural killer cells, basophils, mast cells, and eosinophils, but differs from MCP-1, which is not active on eosinophils. MCP-2 has been proposed to interact with multiple C-C chemokine receptors, including those used by MCP- 1 and MCP-3. However, since leukocytes express a multiplicity of chemokine receptors with promiscuous binding and functional properties, it is difficult to identify the receptors used by a given ligand on these cells.