Figure 3. Intracellular cytokine staining followed by flow cytometry analysis to determine the number of E6-specific CD8⁺ T cells and Pan HLA-DR reactive epitope (PADRE)–specific CD4⁺ T cells in vaccinated mice.

C57BL/6 mice (five per group) were immunized twice intradermally using a gene gun with 2 μg per mouse of Ii DNA, Ii DNA plus SCT-E6 DNA, Ii-PADRE DNA, or Ii-PADRE DNA plus SCT-E6 DNA, with a 1-week interval. Splenocytes from vaccinated mice were harvested 1 week after the second vaccination and stimulated with E6 or PADRE peptide. Splenocytes without peptide stimulation were used as a negative control. The splenocytes were stained for CD8 or CD4 and intracellular interferon-γ (IFN-γ). (a, b) Representative figures of the flow cytometry data. The numbers in the upper right corner represent the number of (a) E6-specific CD8⁺ T cells or (b) PADRE-specific CD4⁺ T cells per 3 × 10⁵ splenocytes acquired. (c, d) Bar graph depicting the numbers of (a) E6-specific CD8⁺ T-cells or (d) PADRE-specific CD4⁺ T cells per 3 × 10⁵ splenocytes (means ± SE). The data presented in this figure are from one representative experiment of two performed.