ELISPOT allows detection of single IFN-γ-secreting cell, but the use of unseparated spleen cells removes the advantages of the method due to a high back ground of IFN-γ-production and uncertainty of the phenotype of secreting cells (CD4, CD8 or NK).We used high purity sorted CD4 and CD8 cells.For in vitro restimulation of CD8 T-cells, we used dendritic cells that present antigenic epitopes of M2, NP or of adenovirus in the context of MHC class I. In this instance, dendritic cells were transduced with Ad5-tet-M2, Ad5-tet-NP or Ad5-null, respectively.For restimulation of CD4 T-cells in vitro, we used dendritic cells that present antigenic M2 or NP epitopes in the context of MHC class II. For this purpose, dendritic cells were additionally activated by lipopolysaccharide E. coli (1 μg/ml) and were loaded with recombinant protein NP or M2e peptide..