Monocyte Chemoattractant Protein-1 (MCP-1)/CCL2 Induces the Chemotactic Activity of Human Eosinophils

Eosinophil is an improtant leukocyte in the development of various inflammatory diseases. Monocyte chemoattractant protein-1 (MCP-1) acts as a key regulator on monocyte movement, and activation of T cells and NK cells. However, the role of MCP-1 in eosinophils remains to be solved. In the present study, we examined the effect of MCP-1 on eosinophil migration, using human eosinophilic EoL-1 cells as an in vitro model of eosinophils. The surface expression of CCR2 in EoL-1 cells was little detected but MCP-1 strongly induced EoL-1 cell migration in a dose-dependent manner. Increased chemotactic activity due to MCP-1 was blocked by pertussis toxin, a $G_i/G_o$ protein inhibitor and U73122, a phospholipase C (PLC) inhibitor. These results suggest that MCP-1 activates $G_i/G_o$ protein and PLC and this signal pathway is involved in eosinphil movement. This finding supports the elucidation of pathogenic mechanism of eosinophilic inflammation such as asthma and atopic dermatitis.