The above findings become important when considering how the ex vivo GrB response to influenza vaccination changes the balance between CD8+ T cells that co-express GrB and Perf and those that do not express Perf when activated ex vivo. In this study, we showed that the ex vivo GrB response to influenza vaccination did not predict risk for LCII but was robustly stimulated following influenza infection, consistent with re-stimulation of T-cell memory. This evidence concerns the gene FABP9 and influenza.