DCs loaded with killed breast cancer cells induce differentiation of effector CTLs. CD8+T cells primed, as described in Figure 1, were assessed in a standard 51Cr release assay using as targets the HLA-A*0201+ MCF7 cells used to load DCs and NK sensitive K562 cells. (a) CD8+ T cells primed by DCs loaded with MCF7 cell bodies exhibit cytotoxic activity against MCF7 used for priming but not against NK sensitive K562 cells. Three separate experiments are represented, indicated by different symbols: filled symbols indicate lysis of MCF7 breast cancer cells, and empty symbols indicate lysis of control K562 cells in the same experiment. (b) Cytotoxic activity was blocked by adding anti-MHC class I antibody (HLA-ABC) but not by adding relevant isotype control (IgG2a). Each value represents the mean from triplicate wells. Representative of three experiments performed. CTL, cytotoxic T lymphocyte; DC, dendritic cell; E:T, effector:target.