PD-L siRNA-silenced DCs show an increased capacity to stimulate KLH-specific T-cell proliferation and cytokine production in vaccinated cancer patients. Autologous PD-L knockdown DCs pulsed with or without KLH were cocultured with PBMCs from vaccinated MM patients at a stimulation ratio of 0.1:1. (A) At day 5, [³H]-thymidine was added to the culture, and the following day, T-cell proliferation capacity was determined by measuring [³H]-thymidine incorporation. Representative data of 2 of 5 patients are shown, and bars are depicted as mean ± SD. CPM indicates counts per minute. (B) IFN-γ levels were measured in the supernatant at day 5 of the coculture. Representative data of 2 of 5 patients are shown, and bars are depicted as mean ± SD. (C) IL-2 levels were measured in coculture supernatant of days 1 and 5. Representative data of 2 of 5 patients are shown. Statistical analysis was performed using one-way ANOVA, followed by a Bonferroni post-hoc test. *P < .05, **P < .01, ***P < .001.