Given that lung NK cells in mice infected with P. aeruginosa produced increased IFN-γ through NKG2D-mediated activation (17), a phenotype similar to influenza-induced exacerbations, it would be fascinating to investigate the precise effect of P. aeruginosa-only infections on COPD exacerbations utilizing murine experiments and to explore the role of NK cell-related NKG2D and IFN-γ in this situation. This evidence concerns the gene KLRK1 and influenza.