Accumulation of memory LCMV-specific CD8 T cells in HP mice. (A) Splenocytes were harvested from HP and WT mice 6 months after infection and then stimulated with LCMV-specific peptides for 5 hours. After stimulation, CD8 and CD4 T cells (left; means ± SD) and CD8⁺CD44⁺IFNγ⁺ cells recognizing each peptide were counted (right; means ± SD). The total percentage of LCMV-specific memory CD8 T cells for GP-33, GP-92, GP-118, NP-205, GP-276, and NP-396 in the CD8 T-cell resting memory pool is shown in the right panel (means ± SD). This is a representative result from 3 repeated experiments with 2 to 5 mice per group. (B) Dot plots show LCMV-specific CD8 T cells from a representative LCMV-immune HP mouse and a WT mouse. Numbers refer to percentage of cells in designated quadrants. (C) The expression of surface markers on NP-396 tetramer-positive cells. Splenocytes were harvested from HP and WT mice 2 to 6 months after LCMV infection. Staining is shown for gated tetramer-positive cells (NP-205, GP-276, and NP-396), except for stains for CD27 and Bcl-2, in which CD8⁺ NP-396–specific IFNγ⁺ cells were gated. Similar expression patterns of surface markers and Bcl-2 on NP-396 CD8 T cells harvested from HP and WT mice 2 to 6 months after infection were seen. This is a representative result of NP-396–specific cells from 4 experiments with 1 to 2 mice per group.