PD-L knockdown DCs show enhanced stimulation of allogeneic T cells. Immature DCs were electroporated with 0.25 nmol of each single siRNA or 0.125 nmol of each siRNA in case of double knockdown. After 2 days of maturation, DCs were mixed with allogeneic T cells. (A) At day 5 of coculture, [³H]-thymidine was added to the culture, and the following day, T-cell proliferation capacity was determined by measuring [³H]-thymidine incorporation. Data are depicted as mean ± SD and are representative for 2 different donors. CPM = counts per minute. (B) IFN-γ levels were measured in the supernatant at day 5 of coculture using ELISA. Data are depicted as mean ± SD and are representative for 3 different donors. (C) Cytokines produced by CD4⁺ and CD8⁺ T cells of the same donor stimulated with allogeneic DCs at a ratio of 1:0.1 were analyzed simultaneously at days 1-5 of the coculture. Statistical analysis was performed using one-way ANOVA, followed by a Bonferroni post-hoc test. *P < .05, **P < .01, ***P < .001.