Fig. 7.
Production of IFN-γ by the indicated peptides in mice vaccinated with Top2αCRNA/DC, and the antitumor effect of p1327 peptide-pulsed DC. a Production of IFN-γ by peptide epitopes derived from Top2αC. Five Top2αC-derived peptides were selected that bind MHC class I molecules (H-2Kb) with a high score using the BIMAS and SYFPEITHI programs. Splenocytes from mice vaccinated with Top2αCRNA/DC were incubated with individual peptides (1 μg/ml) for 3 days. The level of IFN-γ production was measured by ELISA. The statistical significance was evaluated using a t test. *P < 0.05 (T cell only vs. p1327). The data are representative of three independent experiments. b Tumor growth by p1327-pulsed DC (p1327/DC) in the MC-38 subcutaneous tumor model. Two days after MC-38 tumor cell inoculation, mice were vaccinated with p1327/DC once per week for 3 weeks, and tumor volume was measured every 5 days. The statistical significance was evaluated using a t test. *P < 0.05 (DC vs. p1327/DC). Each group consisted of seven mice. c Induction of Top2α-specific immune responses by p1327/DC vaccination. IFN-γ-secreting T cells specific for Top2α in splenocytes from mice vaccinated with p1327/DC were measured with the ELISPOT assay. Splenocytes stimulated with Top2αCRNA/DC and p1327/DC as positive targets, and DC and CEA526/DC as negative targets. The results are given as mean ± SE. The statistical significance was evaluated using a t test of the pooled results of two experiments. *P < 0.05 (DC vs. Top2αCRNA/DC or p1327/DC). d Cytotoxic activity specific for Top2α. Cytotoxic activity was assessed with the 51Cr release assay against MC-38 as Top2α-expressing target at a 40:1 and 20:1 E/T ratio. The statistical significance was evaluated using a t test. *P < 0.05 (DC vs. p1327/DC). The data are representative of two independent experiments