IFNG and viral infectious disease: On Day 7 post transfer, a sizable fraction (one-third) of donor cells concurrently produced multiple proinflammatory cytokines (IFN-γ, TNF-α) upon re-stimulation with the cognate peptide (Figure 4A), resembling the phenotype of so-called ‘polyfunctional effector cells’ which are more effective in controlling viral infections and tumor growth (33, 34).