Figure 4.

Induction of OVA-specific CD8⁺ T cell responses in ret transgenic mice. Tumor free ret transgenic mice (ret) or non-transgenic littermates (wt) were immunized with expression plasmid pcDNA3.1-OVA. Control mice were injected with PBS. Frequencies and functional activities of OVA-specific spleen CD8⁺ T cells were analyzed ex vivo by tetramer staining (a) and IFN-γ ELISPOT assays (b, c); (a). Representative dot plots for tetramer staining are shown; (b, c). Cumulative data (mean ± SEM; 9–11 mice per group) for IFN-γ secreting CD8⁺ T cells are presented as numbers of IFN-γ spots among 5 × 10⁵ splenocytes.