Improved cytolytic function following stimulation with OX40L mRNA–cotransfected DCs. (A) Priming of PSA epitope–specific CTLs using PSA mRNA– or PSA-mRNA/OX40L mRNA–cotransfected DCs as stimulators. CTLs were generated using the indicated stimulators. After 7 days, CTLs were restimulated with PSA-HLA A0201 epitope VISNDVCAQV or control peptide HLSTAFARV, and interferon-γ release was determined by ELISA. (B) PBMCs from a healthy HLA-A0201–positive volunteer were stimulated twice with lymph node carcinoma of the prostate (LNCaP) RNA–transfected DCs (□) or with LNCaP/OX40L mRNA–cotransfected DCs (▪) to generate CTLs. These CTLs were then used in cytolytic assays using DC targets transfected with the following mRNAs: LNCaP RNA, PSA mRNA, GFP mRNA, and OX40L mRNA. Representative results from 3 healthy donors are shown. Results are presented as the mean value of cytokine secretion or target cell lysis with SD (error bars) calculated from triplicate wells.