NOS2 and allergic disease: Furthermore the immune-cell production of various cytokines, like IL-1, IL-6, IL-8, IFN-γ, and TNF-α, can be inhibited by iNOS-derived NO [27], thus emphasizing the connection between high arginase 2 activity, low NO levels, and high IFN-γ, IL-6, and IL-8 demonstrated in patients with non-asthmatic sinusitis without allergy.