Patient-derived hepatitis C virus inhibits CD4+ but not CD8+ T lymphocyte proliferation in primary T cells

Background: Hepatitis C virus (HCV) can replicate in cells of the immune system and productively propagate in primary T lymphocytes in vitro. We aimed to determine whether exposure to authentic, patient-derived HCV can modify the proliferation capacity, susceptibility to apoptosis and phenotype of T cells. Methods: Primary total T cells from a healthy donor were used as targets and plasma-derived HCV from patients with chronic hepatitis C served as inocula. T cell phenotype was determined prior to and at different time points after exposure to HCV. T cell proliferation and apoptosis were measured by flow cytometry-based assays. Results: The HCV inocula that induced the highest intracellular expression of HCV also caused a greatest shift in the T cell phenotype from predominantly CD4-positive to CD8-positive. This shift was associated with inhibition of CD4(+) but not CD8(+) T cell proliferation and did not coincide with altered apoptotic death of either cell subset. Conclusions: The data obtained imply that exposure to native HCV can have an impact on the relative frequencies of CD4(+) and CD8(+) T cells by selectively suppressing CD4(+) T lymphocyte proliferation and this may occur in both the presence and the absence of measurable HCV replication in these cells. If the virus exerts a similar effect in vivo, it may contribute to the impairment of virus-specific T cell response by altering cooperation between immune cell subsets.