FIGURE 5.

Anti-4-1BB promotes the accumulation of memory CD8 T cells following VACV peptide immunization. WT mice were immunized s.c. at the base of the tail with 2 μg of B8R peptide in IFA and 1 day later treated with 25 or 150 μg anti-4-1BB or control Rat IgG. Control groups received adjuvant but no peptide and antibody (PBS). (A) Gated CD8⁺CD44⁺ cells and B8R-tetramer-positive CD8⁺ cells in spleens were stained for 4-1BB on days 3, 5, and 7 post-immunization. (B,C) Three weeks after immunization: (B) cells from lung and spleen were stained with anti-CD8, -CD44, and B8R-tetramer. Left: Representative dot plots of gated CD8⁺ cells. The numbers indicate the percentage of CD8⁺CD44⁺B8R-tetramer-positive cells. Right: Total number of CD8⁺CD44⁺B8R-tetramer-positive cells in the lung and spleen; (C) cells from lung and spleen were stimulated with B8R peptide and stained for intracellular IFN-γ. Total numbers of CD8⁺IFN-γ⁺ cells were calculated. Data represent mean value ± SEM from n = 5 mice. Similar results were reproduced in two separate experiments. Statistical significance. *p < 0.05.