Chemokines are a family of low molecular weight secreted proteins that act as leukocyte specifie chemoattractants. There are over 40 known chemokines which can be divided into four families: CXC, CC, C and CX3C. The CC-chemokines MCP-1,2,3,4 bind and activate CCR2 receptors. CCR2 receptors belong to the GPCR family and couple to the Gi signal pathway. CCR2 receptors are expressed on monocytes, macrophages, basophils, mast cells, T lymphocytes, NK cells and dendritic cells. There are two alternatively spliced forms of CCR2 receptors CCR2A and CCR2B, which differ only in their carboxyl-terminal tails. CCR2 receptors plays important roles in the recruitment of monocytes/macrophages, T cells and relates to many diseases such as inflammation, HIV, and pulmonary fibrosis.