During bacterial infection, Mon1 monocytes are deployed at sites of inflammation, where they recognize and phagocytize pathogens and secrete high levels of pro-inflammatory cytokines (IL-1β, IL-6) and low levels of anti-inflammatory cytokines (IL-10) by secreting monocyte chemotactic protein-1 (MCP1) and CCL2 [56]. This evidence concerns the gene CCL2 and bacterial infectious disease.