Localization of hepatitis C virus antigens in liver and skin tissues of chronic hepatitis C virus-infected patients with mixed cryoglobulinemia.

Skin and/or liver biopsy specimens were obtained from the following patients: 15 anti-hepatitis C virus (HCV), HCV RNA-positive patients and 3 anti-HCV, HCV RNA-negative patients with type II mixed cryoglobulinemia (MC); 7 anti-HCV, HCV RNA-positive patients with chronic active liver disease (CALD); 5 anti-HCV, HCV RNA-negative patients with noncryoglobulinemic vasculitis; and 7 anti-HCV, HCV RNA-negative patients with lichen ruber planus. A pool of murine monoclonal antibodies (MAbs) developed against c22-3, c33c, and c100-3 proteins was used to detect HCV-related antigens (Ags) by indirect immunohistochemistry. Acid electroelution (AEE) of tissue sections was performed to enhance the sensitivity of the immunohistochemical method. In anti-HCV-positive MC patients, specific HCV-related Ags were detected in the small vessels of the skin and in the cytoplasm of hepatocytes. Prior AEE of biopsy sections allowed detection of HCV Ags in 6 of 15 (40%) skin biopsy and in 9 of 14 (64.3%) liver biopsy specimens. HCV immunoreactive deposits in the skin displayed two immunohistochemical patterns: (1) coarse intraluminal material associated with dermal inflammatory infiltrates and intravascular deposition of eosinophilic hyaline material; and (2) reactivity confined to the vessel wall in the context of an apparently normal tissue. Immunoglobulin (Ig) G and IgM deposition in the skin showed immunohistochemical features comparable with those found for HCV Ag deposits.(ABSTRACT TRUNCATED AT 250 WORDS)