Figure 4.

Immunization of DCT-deficient mice with AdhDCTΔVYD abrogates CD4⁺ T cell–mediated tumor protection while T-cell responses to the known helper CD4 epitopes are maintained. (a,b) T-cell responses to the known (a) CD4 epitopes (hDCT_89–101 and hDCT_242–254) and (b) CD8 epitopes (hDCT_180–188 and hDCT_342–351) were assessed via intracellular cytokine staining. Results are shown as mean ± SEM from 10 mice pooled from two separate experiments and represent the absolute number of antigen-specific cells per spleen (*P < 0.05 and **P < 0.0005 compared to AdhDCT; NS, not significant). (c) DCT-deficient mice (n = 10–15) were immunized intramuscularly with 10⁸ plaque-forming units of AdControl, AdhDCT, or AdhDCTΔVYD. Mice were challenged subcutaneously with 2 × 10⁴ B16F10 cells 7 days after immunization. Depletion of CD8⁺ T cells was performed by intraperitoneal injection of purified 2.43 antibodies starting on 3 days and 1 day prior to tumor challenge and subsequently administered once a week until tumors developed. A rat IgG was used as control treatment.