Intrahepatic mononuclear cell populations and MHC antigen expression in patients with chronic hepatitis C [correction of B]: effect of interferon-alpha.

Twenty-four subjects with chronic HCV infection were treated with IFN for six months. Liver biopsies were obtained before and after therapy. The number of mononuclear cells staining for CD3, CD4, CD8, 3G8, and the number of mononuclear cells, liver cells, and bile duct cells staining for class I and II MHC antigens in the biopsies was determined. NK cells increased from 16 +/- 3 to 28 +/- 3 cells per 5 high-power fields (HFP) (P < or = 0.03). The number of bile duct cells expressing class I and II MHC Ag and liver cells expressing class II MHC Ag increased (all P < or = 0.03). The only parameter that distinguished responders from nonresponders was the number of NK cells. Following IFN withdrawal, expression of these antigens declined. Based upon these data, it is concluded that IFN treatment of HCV increases: (1) the NK cells number; (2) the expression of class I MHC Ag on bile duct cells and the expression of class II MHC Ag on liver and bile duct cells; and (3) with IFN withdrawal, these changes disappear.