CD8 T cells at peak of response secrete effector cytokines against viral and tumor Ags. A. Representative example of the ability of CD8 T cells at peak of response to produce IFN-γ, IL-2 and/or TNF-α and to express perforin by ICS and polychromatic flow cytometry. Profiles are gated on viable CD3+CD8+ T cells. B. PBMCs from melanoma patients at peak of response following ACT and peptide vaccination were restimulated in vitro by T2 cells pulsed with MART-126–35 peptide. Following 1 weekly restimulation, ELISpot assays measured IFN-γ secretion after overnight exposure to the respective peptide-loaded (≡), unloaded T2 (░), or Me205 (□) targets. Limited cell numbers precluded isolation of CD3+CD8+ T cells for the ELISpot assays. Shown are the averaged data (means ± SEM) from 4 independent experiments each one performed in triplicate for the number of IFN-γ spot forming cells (SFC) per triplicate of 105 input cells at 30:1 (E:T) ratio.