High transgene expression is mainly observed in the population of mature DCs. (A) Day-6 DCs were composed of CD11c⁺ CD86^– (immature DCs) and CD11c⁺ CD86⁺ cells (mature DCs). The phenotype of purified immature DCs and mature DCs gated on CD11c⁺ cells is displayed. Numbers represent percentages of positive cells and MFI (between parentheses). Results from 1 of 10 representative experiments are shown. (B-C) Transgene expression in DCs is related to their maturation stage. (B) Luciferase expression in purified immature DCs or mature DCs shows that most of the transgenic luciferase was expressed in the population of mature DCs (P < .001). Negative controls are DCs transfected with plasmid backbone. Means ± 1 SD from 3 independent experiments are shown. * indicates P < .001; **, P < .0001. (C) Expression of OVA-TR is preferentially observed on the cell membranes of mature DCs. Numbers in graphs are percentages of OVA-positive DCs and MFI (between parentheses).