FIGURE 4.

Anti-4-1BB treatment does not enhance CD8 T cell memory to VACV-Lister. Mice were infected i.p. with 2.5 × 10⁵ PFU/mouse of VACV-Lister. One day later, mice were treated with 25 μg (A–C) or 100 μg (A) of control rat IgG or anti-4-1BB and responses assessed after 35 days. (A) Spleen (upper panel) and lung (lower panel) cells were stained with CD8, CD44, and B8R tetramer (left). Total numbers of CD8⁺ B8R-tetramer-positive cells in spleens (right). (B,C) CD8 T cell functionality in the spleen (B) and lung (C) was assessed by intracellular IFN-γ staining after stimulation with the indicated VACV peptides. Top: Representative plots of cytokine staining, gating on CD8⁺ T cells. Bottom: Total numbers of CD8⁺ IFN-γ⁺ cells per tissue. The results are means and SEM (n = 4 mice/group) from one experiment. Similar results were obtained in two separate experiments. Statistical significance. *p < 0.05.