Depletion of CD8 T cells during priming results in reduced DC activation and NK cell activity. (A) Lymphocytes were isolated from Peyer patches as described in Figure 1 and were analyzed on the CD11c⁺I-A/I-E⁺ population. Shaded areas indicate pBud control mice. Their average mean fluorescence intensity (MFI) and SD are shown as the gray numbers, and pH60/Surv-vaccinated mice are represented by the black line and black number. (Left) No CD8 depletion. (Right) CD8 depletion. Numbers indicate average of MFI and SD of 2 samples within the group in the same experiment. All overlay histograms are presented as percentage of maximum on the y-axis. ^*P < .01 compared with the pBud control group. (B) Mice vaccinated with pH60/Surv were either undepleted (none, ▪) or depleted of CD8 T cells starting 1 day before the first vaccination (prevaccination, ) or 3 days after the second vaccination (postvaccination, ○). Mice were killed 2 weeks after the second vaccination. Freshly isolated splenocytes were used in a standard ⁵¹Cr-release assay against Yac-1 NK target cells. ^*P < .01 compared with nondepletion or postvaccination depletion groups. (Top panels) DX5 and CD4 distribution among splenocytes from undepleted or CD8-depleted mice. (C) Splenocytes freshly isolated from vaccinated mice were either undepleted (▪) or depleted of NK cells (⋄) and used in a standard ⁵¹Cr-release assay against Yac-1 cells. ^*P < .01 compared with the nondepletion group. All experiments were repeated at least once and yielded similar results.