FIG. 4.

The efficient induction of CTL activity and the tumor-specific immune response were enhanced by combination treatment with TMZ and tumor antigen-pulsed DCs in the GL26 glioma model. (A to D) On day 35 after the inoculation of GL26 (1 × 10⁴) cells, splenocytes from each group were harvested in vitro and restimulated with 4% paraformaldehyde and prefixed with GL26 cells as effector cells for 5 days. These effector cells were then assessed for their cytolytic activity against target cells (GL26, EL4, CT26, and YAC-1 cells) labeled with ⁵¹Cr. The ⁵¹Cr release was measured after 4 h of incubation at a variety of E/T ratios. (E) The numbers of IFN-γ-secreting splenocytes from treated mice, as described above, were measured by the ELISPOT assay after restimulation in vitro with 4% paraformaldehyde and prefixation with GL26 cells for 5 days. The results represent the mean number of IFN-γ spots per 10⁵ splenocytes from individually tested mice. *, statistically significant (P < 0.01) by Student's t test compared with the results for all other groups. The results are given as the means ± standard errors and are representative of those from two independent experiments.