Peptide pool–specific T-cell lines respond to endogenously processed antigen. T-cell lines specific for AdV hexon protein, EBV LMP2, A fumigatus p41 peptide, C albicans MP65, or multipathogen-specific lines were restimulated with peptide pool or natural antigen (AdV lysate, 2 different partially matched EBV-transfected LCLs, A fumigatus cell extract, and ethanol-inactivated C albicans) and responses assessed by IFN-γ ELISA. Medians and range of at least 5 independent experiments of 3 different donors are shown. All differences between single- versus multipathogen-specific line and stimulation with peptide versus natural antigen were statistically not significant.