FIGURE 6.

Memory CD8 T cells from γHV68 persistently infected mice survive in an environment free of cognate γHV68 Ags, and mount a proliferative response during recall to γHV68. B6.PL mice (CD90.1) received 1 × 10⁶ CFSE-labeled CD44⁺ CD8⁺ T cells isolated from the spleens of B6 mice (CD90.2) that have been infected with γHV68 for at least 3 mo (γHV68 memory; ■) or from noninfected age-matched controls (irrelevant memory; □). A, Bar diagrams represent the frequency of CD90.2⁺CD8⁺ T cells in the bone marrow, MLN, and spleen 30 days after adoptive cell transfer. B, Bar diagrams show the total cell number of CD90.2⁺CD8⁺ T cells in the bone marrow, MLN, and spleen 30 days after adoptive transfer. Recipient mice were rested for 30 days without Ag after adoptive cell transfer and subsequently infected with γHV68. C, Bar diagrams represent the frequency of donor CD90.2⁺CD8⁺T cells in PBLs on day 0 (before γHV68 infection) and on day 14 after γHV68 infection. Bars represent the mean value of three experimental animals, and error bars indicate SEM. Similar results were obtained in two independent experiments.