The levels of these PAHs were correlated with asthma-related biomarkers including immunoglobulin E (IgE), resistin, granulocyte–macrophage colony-stimulating factor (GMCSF) and interferon gamma (IFN-γ) as well as the cytokines; interleukin (IL)-4, IL-5, IL-8 (CXCL8) and IL-10. This evidence concerns the gene IFNG and asthma.