Figure 4.

The unusual phenotype of vaccinia virus–specific CD8⁺ T cells is not a consequence of in vitro stimulation. (A) Representative KVD, CLT, and ILD tetramer staining of HLA-A2⁺ vaccinees after Dryvax challenge plotted as tetramer versus side scatter–area (SSC-A). Numbers indicate the percentage of CD8⁺ T cells that are tetramer positive. CD27 and CD45RO expression on tetramer-binding cells is shown as red contour plots overlayed on density plots of the total CD8⁺ T cell population. (B) PBMCs from HLA-A2⁺ vaccinees were stimulated with peptide for 6 h or vaccinia virus for 9 h. Data from a representative stimulation with KVD is displayed (as in Fig. 1 D). The phenotype of vaccinia virus–specific CD8⁺ T cells is shown as a red contour plot overlayed on a density plot of the total CD8⁺ T cell population. To best separate the CD27 high, intermediate, and low populations, a PE-conjugated antibody was used for staining. To accommodate this change from the standard antibody panel, the anti–MIP-1β antibody was omitted. Therefore, the contour plot shows the phenotype of CD107a⁺IFN-γ⁺IL-2⁺TNF-α⁺ CD8⁺ T cells, which (as shown by the bar graph) also produce MIP-1β. (C) PBMCs from HIV-1–infected individuals were stimulated for 6 h with overlapping Gag peptides or for 9 h with Gag recombinant vaccinia virus. Data from a representative individual is shown. The contour plots show the phenotype of CD107a⁺IFN-γ⁺IL-2⁻TNF-α⁺ CD8⁺ T cells.