CpG-C ISS lose their ability to induce IFN-α from human PDCs while retaining the ability to induce maturation when encapsulated into pH 5.75 liposomes. CpG-C ISS lose their ability to induce IFN-α from human PDCs while retaining the ability to induce maturation when encapsulated into pH 5.75 liposomes. Purified PDCs (5 × 104 cells) were cultured with CpG-C (0.5 μg/ml) alone, empty liposomes, CpG-C mixed with empty liposomes, and with CpG-C encapsulated into two different liposome preparations (pH 4.5 or pH 5.75 sensitive) as described in Fig 7. (A) After 16 h, supernatants were harvested, IFN-α production was evaluated using immunoassay, and (B and C) cells were characterized for CD80 and CD86 expression by flow cytometry. (B) Representative dot plots. (C) Averages of the cumulative mean fluorescence intensity for four independent donors representative of 10 donors are shown. *, P < 0.05. Cristiana Guiducci et al. J Exp Med 2006;203:1999-2008 © 2006 Rockefeller University Press