FIG. 3.

Functionality of BKV VP1p108 tetramer-binding cells. PBMC from donor ND07 were expanded by in vitro stimulation with the BKV VP1p108 peptide in the presence of 30 U/ml recombinant IL-2. The expanded cell culture was then labeled with BKV VP1p108 Tet-APC and restimulated in culture for 4 h with peptides in the presence of costimulatory antibodies, monensin, and FITC-conjugated antibodies to CD107a and CD107b (α-CD107a/b-FITC) before permeabilization and labeling with a CyChrome-conjugated antibody to CD8 and a PE-conjugated antibody to IFN-γ (α-IFN-γ-PE). For more details, see Materials and Methods. For flow analysis, a primary gate was set on lymphocytes by forward versus side scatter, and in the case of the four CD107 versus IFN-γ plots, a primary gate was set on tetramer-positive cells. The values in the plot quadrants indicate cell numbers as a percentage of CD8⁺/BKV VP1p108 tetramer-positive lymphocytes.