Background and aim: The hepatitis C virus (HCV) receptor CD81 is overexpressed on peripheral blood mononuclear cells (PBMC) in patients chronically infected with HCV compared with healthy controls, and expression declines during antiviral therapy. The aim of this study was to prospectively investigate CD81 expression on PBMC for early discrimination between sustained virologic response (SVR) and relapse (REL) to pegylated interferon alfa-2b and ribavirin treatment.
Methods: Sixty-one patients with chronic HCV infection (genotype, GT, 1 and low baseline viremia <600,000 IU/ml, n = 30; GT 2 or 3, n = 31) were investigated. CD81 expression on CD4(+), CD8(+), CD19(+), and CD56(+) cells was measured at baseline, therapy week (TW) 4 and 12 during antiviral therapy by fluorescence-activated cell sorting (FACS) analysis.
Results: Baseline levels of CD81 on CD4(+), CD8(+), and CD56(+) cells were similar between patients who achieved a SVR (n = 42) and those who relapsed (n = 19). On CD19(+) cells, baseline CD81 expression was higher in patients with SVR than in patients with virologic relapse (REL) (p < 0.006). A cutoff value of 720 relative fluorescence units (RFU) discriminated correctly between SVR and REL with a sensitivity and specificity of 73.7% and 66.7%, respectively. SVR patients showed a significant decline of CD81 expression on CD4(+), CD8(+), CD19(+), and CD56(+) cells (p < 0.01 for all) while in REL patients a significant decline of CD81 expression was observed on CD8(+) and CD56(+) cells, only (p = 0.050 and p = 0.038, respectively).
Conclusions: The current study confirms significant down-regulation of CD81 expression on different lymphocyte subpopulations during pegylated interferon alfa-based antiviral therapy in patients with chronic hepatitis C. Baseline CD81 expression on CD19(+) cells was found to discriminate between SVR and REL.