Fig. 2.

Specific CTL activity induced by various types of immunization. Mice were immunized at days − 20 and − 10 with PBS (n = 6), CP-peptides (n = 4), TFA-peptides (n = 4), unloaded mature DC (n = 10), DC/CP (n = 6), or DC/TFA (n = 10) before the injection of a lethal dose of C1498 cells. Seven days post-tumor cells challenge, spleen cells from recipient mice were harvested and stimulated in vitro with irradiated C1498 cells and rhIL-2. After 6 days of culture, cytotoxic activity was determined by 4-h ⁵¹Cr release cytotoxicity assay using C1498, A20, and YAC-1 as target cells. The results show the mean of three independent experiments performed on the pool of splenocytes isolated from a variable number of vaccinated mice (4–10 mice). Vaccination with DC/TFA induced a more specific recognition of autologous C1498 cells than DC/CP. *P < 0.05, **P < 0.02, and ***P < 0.01