Analysis of cellular uptake of RNA mediated by HL5B. (A) Human pDCs were stimulated with HL5B or control IgG (100 ng/mL each) in fresh medium for 10 minutes. Thereafter, the medium was removed and the cells were washed twice before adding, either fresh medium or the conditioned medium in which the cells had been cultured before. Relative expression of TNFα mRNA was normalized to β-actin. (B-D) Human pDCs (B) or CD11c⁺ cells from C57BL/6 (C) or Tlr ^−/− mice (D) were pretreated for 10 minutes with either HL5B or IgG. Uptake of fluorescently labeled RNA40 was measured by flow cytometry.