FIG. 2.

Functional analysis of CD8⁺ T cells from mice immunized with DNA vaccine with or without delayed plasmid IL-12 administration. Groups of BALB/c mice were immunized with 50 μg of sham PMV plasmid, 50 μg of PMV-gp120 alone, or 50 μg of PMV-gp120 plus 200 μg of PMV-IL-12 on day (d.) 10 following vaccine administration. Spleen cells were harvested from individual mice on day 18 postimmunization for functional analysis. (A) Total splenocytes or splenocytes depleted (Depl.) of CD8⁺ or CD4⁺ T cells were evaluated for IFN-γ production in an ELISPOT assay following stimulation with the gp120-derived p18 epitope peptide or a pool of 47 overlapping peptides spanning the HIV-1 IIIB gp120 protein. Data are presented as the mean number of antigen-specific spots per 10⁶ spleen cells ± SEM with four mice per group. (B) Spleen cells from mice immunized with sham PMV plasmid (triangles), PMV-gp120 alone (circles), or PMV-gp120 plus plasmid IL-12 DNA (squares) were cultured for 7 days in the presence of 10 ng of p18 peptide per ml. Cells were then harvested and used as effectors in a ⁵¹Cr release assay to assess lysis of P815 tumor cell targets incubated overnight in the presence of medium alone (open symbols) or p18 peptide (filled symbols). Results are expressed as the percent specific ⁵¹Cr release and are the means ± SEM of four mice per group. E:T ratio, effector-to-target ratio.