Figure 3.

Functional properties of the in vivo–generated PSA-specific CTLs. PBMCs derived from study patients at baseline (white bars) or after immunotherapy (black bars) were stimulated twice with PSA RNA (a) or GFP RNA–transfected DCs (b). Using standard ⁵¹Cr microcytotoxicity assays, lytic activities against PSA RNA– or GFP RNA–transfected DC targets were calculated. (c) Experiments in which MHC class I– or CD8-specific mAb’s were used to inhibit recognition and lysis of PSA RNA-loaded DC targets. The addition of these mAb but not isotype control mAb (Control mulgG1) during incubation of effector and target cells (40:1 E/T ratio) resulted in significant inhibition of PSA-specific cytolytic activity, suggesting that the observed responses are predominately mediated by MHC class I–restricted CD8 CTL.