Normal functional capacity in circulating myeloid and plasmacytoid dendritic cells in patients with chronic hepatitis C

Initial reports analyzing dendritic cell (DC) function in patients with hepatitis C virus (HCV) infection have been controversial. Here, we enumerate and characterize the function of circulating myeloid and plasmacytoid DCs. The results show lower percentages of myeloid DCs (0.62 vs. 0.83; P = .05) and plasmacytoid DCs (0.11 vs. 0.34; P = .004) in patients with chronic HCV infection than in healthy, non-HCV-infected individuals. Despite the lower numbers of circulating myeloid DCs present, no phenotypic or functional defects were identified. The lower percentage of plasmacytoid DCs resulted in decreased absolute interferon (IFN)-α production; however, when analyzed on a per-cell basis, plasmacytoid DCs from HCV-infected patients generated levels of IFN-α equivalent to those generated by DCs from healthy, non-HCV-infected individuals. Contrary to data from previous models (which attributed HCV pathogenesis to defects in the DC compartment), our data reveal functional DC subsets in patients with chronic HCV infection. These results are encouraging for DC-based HCV immunotherapy trials.