Photomicrograph of developed wells after an IFN-gamma ELISPOT assay assessing the reactivity of purified CD8+ T cells against influenza matrix peptide or predicted DBL/MCF2 peptides pulsed on to T2 cells. (a) Background control, (b) GILGFVFTL (influenza matrix peptide), (c) YLLKPVQRI (DBL180), (d) AMLDLLKSV (DBL217), and (e) MIMQGGFSV (DBL247). The number of background spots (CD8+ cells with T2 cells/RPMI/DMSO but without peptide) varied from 11 to 12 spots per 100,000 cells and were subtracted. The mean of triplicate experiments ± 1 standard deviation is shown.