Detection of hepatitis C virus (HCV) negative strand RNA and NS3 protein in peripheral blood mononuclear cells (PBMC): CD3(+), CD14(+) and CD19(+)

BACKGROUND: Although hepatitis C virus (HCV) is primarily hepatotropic, markers of HCV replication were detected in peripheral blood mononuclear cells (PBMC) as well as in ex vivo collected tissues and organs. Specific strains of HCV were found to be capable to infect cells of the immune system: T and B cells and monocytes/macrophages as well as cell lines in vitro. The direct invasion of cells of the immune system by the virus may be responsible for extrahepatic consequences of HCV infection: cryoglobulinemia and non-Hodgkin’s lymphoma. The aim of the present study was to determine the prevalence of markers of HCV infection: negative strand HCV RNA and non-structural NS3 protein in PBMC subpopulations: CD3(+), CD14(+) and CD19(+). The presence of virus and the proportion of affected cells within a particular PBMC fraction could indicate a principal target cell susceptible for HCV. METHODS: PBMC samples were collected from 26 treatment-free patients chronically infected with HCV. PBMC subpopulations: CD3(+), CD14(+), CD19(+) were obtained using positive magnetic separation. The presence of negative strand RNA HCV and viral NS3 protein were analyzed by strand-specific RT-PCR and NS3 immunocytochemistry staining. RESULTS: Negative strand HCV RNA was detectable in 7/26 (27%), whereas NS3 protein in 15/26 (57.6%) of PBMC samples. At least one replication marker was found in 13/26 (50%) of CD3(+) cells then in 8/26 (30.8%) of CD14(+) and CD19(+) cells. The highest percentage of cells harboring viral markers in single specimen was also observed in CD3(+) (2.4%), then in CD19(+) (1.2%), and much lower in CD14(+) (0.4%) cells. CONCLUSIONS: Our results indicate that CD3(+) cells are a dominant site for extrahepatic HCV replication, although other PBMC subpopulations may also support virus replication.