The results demonstrated that the expression and release of IL-8 (interleukin 8, a pro-inflammatory cytokine that has a role in neutrophil activation and has been identified within the pathogenesis and progression of the disease [105]) in response to combined infection and NO2 exposure was significantly higher than the sum of release from the cells that underwent only infection or only NO2 exposure. Here, CXCL8 is linked to infection.