Reactivation of virus-specific CD8⁺ T cells rendered quiescent by IFN-I. EBV-specific T cells maintained in fresh medium alone, IL-15, IFN-α, or IFN-β were reactivated with peptide-pulsed autologous APCs plus exogenous IL-2. Proliferation was determined by tritiated thymidine incorporation 5 days later (A). Error bars refer to the standard error from the mean. IFN-γ (B) and perforin (C) expressions were determined 18 hours and 3 days after reactivation, respectively (gray histograms represent unstimulated control). These results are representative of 3 separate experiments. (B-C) Percentages shown refer to the proportion of cytokine-secreting T cells.