Figure 4.
DCTAE vaccines induce tumor-specific immune responses in mice. (A and B) Six-week C57BL/6 mice were i.v. immunized with different vaccines at day 0 and 7 as previously described. (A) Seven days after last immunization, total splenocytes were re-stimulated with LLC tumor cell lysates as described in Methods in the presence of IL-2 for 72 h, and then co-cultured with target cells (LLC cells) at different ratios of effector cells to target cells (E:T ratio) for another 4 h. Tumor-specific in vitro CTL response was analyzed using nonradioactive cytotoxicity assay, and the production of IFN-γ (B) in culture supernatants was measured using ELISA. Tumor-bearing mice were immunized with different vaccines once a week for 3 weeks from day 7 after tumor implantation. The survival rate (C) and tumor volume (D) were monitored every 2-3 days. (E-F) Measurement of subcutaneous tumor weight at 35 days after inoculation. Cell apoptosis in tumor tissue cryostat sections was detected using TUNEL assay (G), and the percentage of apoptotic cells (TUNEL+) was quantified using image J software (H). Bars shown are mean ± SE (n = 5-6), and differences between PBS and other groups are determined using one-way ANOVA analysis. **: p < 0.01. # Differences between two different groups are statistically different, #: p < 0.05; ##: p < 0.01.