Chemokines (chemoattractant cytokines) represent a superfamily of small secreted proteins that function as intercellular messengers to control migration and activation of leukocytes involved in inflammatory reactions and immunity. Furthermore, chemokines are important mediators of many pathologies such as allergic responses, chronic inflammatory and autoimmune diseases, tumor growth and hematopoietic development. The CC-chemokine monocyte chemoattractant protein 1 (MCP-1), also known as monocyte chemotactic and activating factor (MCAF) was characterized as a monocyte-specific chemoattractant that was later shown to attract also T lymphocytes and NK cells. MCP-1 is mainly expressed by macrophages in response to a wide range of cytokines such as IL-6, TNFa and IL-1B, but can, upon stimulation, also be produced by a variety of cells and tissues, such as fibroblasts, endothelial cells or certain tumor cells. Because of its target cell specificity, MCP-1 was postulated to play a pathogenic role in a variety of diseases characterized by mononuclear cell infiltration, including atherosclerosis, rheumatoid arthritis and allergic responses. Elevated levels of MCP-1 have also been found in connection with osseus inflammation and Alzheimer's disease (AD) as well as Myocardial Ischemia and viral infections. In acute and chronic-active multiple sclerosis (MS) lesions immunoreactivity for MCP-1 was increased whereas MCP-1 was found to be significantly reduced in cerebrospinal fluids (CSF) and chronic lesions of patients with MS . In basophils, MCP-1 is highly effective as a stimulus of histamine release but has only weak chemotactic activity. Additionally it has been shown to chemoattract CD4+ and CD8+ T lymphocytes, and expression of the MCP-1 chemokine may affect HIV infection via signalling through the CCR2 receptor .