Fig. 7.
Dose–response inhibition of hepatitis C virus (HCV)-specific interferon (IFN)-γ production by CD4+CD25+ T cell in patients with normal and elevated alanine aminotransferase (ALT). CD4+ T cells were used as effector cells to examine HCV-specific IFN-γ activity as measured by flow cytometry in response to pooled HCV antigens (core, NS3, NS4, NS5: 2 µg/ml each) and anti-CD28 and anti-CD49d monoclonal antibodies in co-culture with CD4+CD25+ T cells at various ratios. Duplicate wells without stimuli were also included to determine the background level of cytokine production. The number of positive events in the absence of antigen stimulation was constantly below 0·01%.