CCL2 and infection: The macrophages are recruited to the place of the infection due to the chemokine CCL2 (MCP-1), as a consequence of its high expression 1–5 d.p.i. This chemokine not only acts as a chemoattractant for macrophages but also has a role in the regulation of TH1/TH2 responses, especially since it promotes the secretion of IL-4, thereby stimulating the TH2 response even more [158].