Serologic testing shows that hepatitis C virus (HCV) may have a role in the pathogenesis of B-cell non-Hodgkin lymphomas (B-cell NHLs). We tried to demonstrate HCV RNA sequences in paraffin-embedded tissue from B-cell NHLs by reverse-transcription double polymerase chain reaction (RT-PCR) and Southern blotting. We studied 31 consecutive cases of B-cell NHLs; lymph nodes from 32 patients with diseases other than B-cell NHL were negative controls. Positive-strand HCV RNA was tested with primers for the 5' untranslated region. Replicative negative strand HCV RNA was tested with strand-specific RT-PCR for the 5' untranslated region. Immunohistochemical staining for HCV was done using an antibody to HCV core protein. Positive-strand HCV RNA was detected in 8 patients with B-cell NHL; negative-strand HCV RNA was detected in 6 of these cases, indicating viral replication. All control cases were negative for HCV RNA. Immunohistochemistry showed no staining of lymphoma cells for HCV core proteins in any case. HCV and B-cell NHLs may be associated. RT-PCR on paraffin-embedded lymphoma tissue is an alternative method of testing for HCV. The value of immunohistochemistry could not be ascertained. The exact role of HCV in the pathogenesis of B-cell NHL needs to be studied further.
The mechanisms of hepatocyte death and the events that lead to a high rate of chronic liver disease in patients infected with hepatitis C virus are not known. We established a HCV replication system in HepG2 cell culture and utilized this model to address the effect of HCV proteins on HepG2 cell growth and viability. After transfection of HepG2 cells with full-length RNA, a truncated RNA, or an antisense RNA, cell proliferation and cell viability were analyzed by thymidine uptake and the trypan blue exclusion method, respectively. Full-length RNA transfected HepG2 cells showed a decrease in cell proliferation and viability compared to cells transfected with HCV truncated RNA and antisense RNA control. A subset of cells expressing HCV proteins underwent apoptosis as documented by morphological studies, ultrastructural analysis, cell cycle analysis by flow cytometry, terminal transferase enzyme mediated end labeling of DNA, and DNA laddering. This study suggests that expression of HCV proteins can lead to cell death by apoptosis, which may be an important event in the pathogenesis of chronic hepatitis C virus infection in humans.
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