Monocyte chemoattractant protein-1 (MCP-1) is a 13 kDa chemokine that regulates migration and infiltration of monocytes/macrophages. The idiopathic inflammatory myopathies, including dermatomyositis (DM), polymyosititis and inclusion body myositis, are a group of autoimmune diseases characterized by chronic lymphocytic and macrophagic infiltration in muscle. MCP-1 is believed to play a major role in the recruitment of these cells, especially in DM. Plasma levels of MCP-1 have also been shown to be increased in patients with high viral load compared with HIV-seropositive subjects with undetectable plasma viral RNA and healthy controls.