Figure 3.

Vaccinia virus–specific CD8⁺ T cells have an unusual phenotype. (A) Several surface markers were included in the multicolor flow cytometry panel to define the phenotypes of vaccinia virus–specific CD8⁺ T cells. To incorporate these markers into the panel, responding cells were identified by staining with Alexa Fluor 680–CD107a and IFN-γ, TNF-α, or IL-2 (each conjugated to APC). A CD27-PE antibody conjugate was used to allow for the best discrimination of expression. The phenotype of CD107a⁺cytokine⁺ CD8⁺ T cells is shown as a red contour plot overlayed on a density plot of the total CD8⁺ T cell population at 1 and 5 mo after Dryvax challenge in a representative individual from the MVA immunization group. (B) The vaccinia virus–specific CD8⁺ T cell phenotype is similar among cells of different functional properties. 5+ (CD107a⁺IFN-γ⁺IL-2⁺ MIP-1β⁺TNF-α⁺), 4+ (CD107a⁺IFN-γ⁺IL-2⁻MIP-1β⁺TNF-α⁺), and 3+ (CD107a⁻IFN-γ⁺IL-2⁻MIP-1β⁺TNF-α⁺) CD8⁺ T cells are overlayed as contour plots on density plots of the total CD8⁺ T cell population.