[Role of hepatitis C virus in mixed cryoglobulinemia in patients with chronic hepatitis].

To evaluate the role played by hepatitis C virus (HCV) in mixed cryoglobulinemia in subjects with chronic hepatitis, we studied 72 consecutive patients: 43 had HCV-related chronic hepatitis, 19 HBV-related chronic hepatitis, and 10 chronic hepatitis of other etiology. We used second generation ELISA and RIBA to test for mixed cryoglobulinemia and anti-HCV antibodies in both serum and cryoprecipitates; HCV RNA were evaluated by "nested" PCR. Serum levels of rheumatoid factor and complement were also determined. The immunoglobulins in the cryoimmunoprecipitate were characterized by immunofixation electrophoresis. Cryoglobulinemia was present in 47% of the patients with chronic hepatitis C but in none of the sera of patients with HBV-related chronic hepatitis nor in those with chronic hepatitis of non-viral etiology. Type II mixed cryoglobulinemia was observed in 45% of the cases, and type III in 55%. HCV RNA and anti-HCV antibodies were present in all the cryoimmunoprecipitates. Ninety-five percent of the cryoglobulinemic patients had serum rheumatoid factor and 80% of them had low serum levels of C4. Our data indicate that mixed cryoglobulinemia is frequently associated with HCV-related chronic hepatitis, and that HCV and anti-HCV antibodies play an essential role in the development of mixed cryoglobulinemia.