Immunostimulation of PBMCs by different siRNA formats. Supernatant from PBMCs treated with 100 nM DOTAP complexed siRNAs (siRNA = standard 19 bp duplex with 2 base 3' overhangs; 19 mer blunt = 19 bp duplex with no overhangs, 21 P/19 G indicates 21 bp passenger strand annealed to a 19 bp guide strand; 19 P/17 G indicates 19 bp passenger strand annealed to a 17 bp guide strand; Dicer = dicer substrate siRNA; 25 mer blunt = 25 bp duplex with no overhangs; 29 mer hairpin = 29 bp hairpin RNA; 29 mer hairpin +3'OH = 29 bp hairpin RNA with 3'-hydroxyl group) for 24 hours was applied to Huh7-Luc cells. Luciferase expression was assayed 24 hours after treatment with supernatant. Each bar represents the mean of triplicate samples. Error bars indicate standard deviation.