Interaction of HCV-LPs with blood DCs. (A) Immunophenotyping of freshly isolated myeloid (pre–DCs 1) and plasmacytoid (pre–DCs 2) pre-DCs from peripheral blood used for HCV-LP binding. Phenotypes of pre-DCs were characterized by flow cytometric analysis of CD1c expression for pre–DCs 1 (left) and CD123 expression for pre–DCs 2 (right). Histograms corresponding to cell surface expression of the indicated molecules (open curves) are overlaid with histograms corresponding to cells incubated with the appropriate isotype control antibody (gray shaded curves). (B-C) HCV-LP binding to pre-DCs and imDCs. Freshly isolated pre-DCs as well as myeloid and plasmacytoid imDCs (imDCs 1 and -2) were incubated with HCV-LPs (HCV-LP E2 concentration ≈ 2 μg/mL) and binding of HCV-LPs was analyzed as described in Figure 1. Flow cytometry histograms of HCV-LP binding to pre-DCs (B) and imDCs (C) are shown (open curves). Background fluorescence (gray shaded curves) was measured as described in “Analysis of cellular HCV-LP binding” using cells incubated with insect cell control preparations.