IFNG and influenza: One study demonstrated pre-activation of natural killer (NK) cells by inactivated H3N2 virus resulted in increased IFN-γ+ NK cells 30 days post-vaccination.8 NK cell-induced inflammation in psoriatic lesions may be based on keratinocyte activation via cytokines including IFN-γ and TNF-α.9 Although Australian influenza vaccines are reformulated annually,10 each formulation received by our patient contained this strain.