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PubMed1999

Autoimmunity and extrahepatic manifestations in hepatitis C virus infection.

Hepatitis C virus (HCV) infection is associated with various extrahepatic manifestations: mixed cryoglobulinaemia, membranoproliferative glomerulonephritis and, in southern Europe, to some extent with porphyria cutanea tarda. The association of haplotype HLA B-8 and DR-3 mixed cryoglobulinaemia and HCV infection has recently been demonstrated. Interferon alpha therapy decreases hepatitis C viraemia and improves the clinical signs and biochemical abnormalities of cryoglobulinaemia. There seems to be a south-north gradient in the prevalence of HCV-associated cryoglobulinaemia. The rare combination of hepatitis C and panarteritis nodosa has still not been confirmed. The sicca syndrome also seems to be associated with hepatitis C virus, but this is not the typical Sjögren syndrome. Existing studies have not answered the question of whether HCV plays a pathogenic role in the development of thyroid dysfunction and autoimmune thyroiditis. There seems to be a genetic predisposition for the manifestations of thyroid disease in the case of hepatitis C infection and interferon therapy. This predominantly affects women with haplotype HLA DR-3. Before beginning interferon therapy, these patients often show thyroid autoantibodies against the thyroid peroxidase and/or thyroglobulin. It is still unclear whether the rare combination of hepatitis C with aplastic anaemia and lymphoma has pathogenic aspects. These haematological manifestations are thought to be induced by the infection of haematopoietic cells with the hepatitis C virus. In rare cases, a stimulated HCV-induced interferon gamma synthesis by haematopoietic stem cells has been shown. Although an epidemiological association of hepatitis C with lichen planus, neuropathies and other diseases has been observed, the aetiological role and the pathogenic involvement of the hepatitis C infection remains unclear. Furthermore, the question of whether these extrahepatic diseases are autoimmune has not been clarified. On the other hand, a number of autoantibodies may be observed during the course of hepatitis C. Of particular interest are liver/kidney microsomal antibodies (LKM). Their occurrence in viral hepatitis may indicate an increased risk for treatment with interferons. In the clinical setting, the presence of these diseases should suggest hepatitis C infection and hepatitis C antibodies should be tested and, if positive, hepatitis C-RNA is indicated. If there is any evidence of an aetiological association of replicative hepatitis C infection and the above-mentioned extrahepatic diseases, antiviral treatment should be considered.

Autoimmune Diseases↗
PubMed2004

Assessment of humoral immune response in patients with chronic hepatitis C virus infection.

Hepatitis C infection is a major public health problem worldwide. Hepatitis C virus (HCV) infection has been identified as a major causative agent of post-transfusion hepatitis. The host immune response to HCV infection is composed of both non- specific immune response, including interferon (IFN) production and natural killer (NK) cell activity and a virus-specific immune response, including humoral and cellular components. Susceptibility to infection has been related to immunological disturbances. Several studies have provided experimental evidence of disorders of both cellular and humoral immunity. Humoral Immunity is dependent mainly on immunoglobulins and little data are available about serum immunoglobulin values in chronic hepatitis C. The present study aimed to evaluate humoral immune response by measuring the concentration of serum immunoglobulin isotypes (IgG, IgM, IgA) and IgG-subclasses level (IgG1-4) in chronic hepatitis C patients and healthy controls. This study included 50 patients with chronic hepatitis C. All of them had positive serum anti-HCV antibodies, positive serum HCV-RNA by PCR, and histologically-proven chronic hepatitis. The results were compared with 25 healthy controls. Total IgG, IgA and IgM were assayed by nephelometry. IgG subclasses were assayed using human IgG subclasses enzyme immunoassay. Serum protein electrophoresis was performed in agarose gel. The results showed that no significant difference in serum immunoglobulin levels were found among patients with chronic hepatitis C of minimal liver damage( Knodell index < or =3) and patients with mild liver disease (Knodell index > 3). A significant increase in total serum IgG, IgG1 and IgG2 levels were found in patients with chronic hepatitis than in healthy controls but no difference was found in IgG3 and IgG4 in both patients and controls. Mean serum IgM was increased in patients with HCV infection compared with healthy controls. No significant difference was found in IgA level in both the patients and healthy controls. Our data revealed an increase of humoral immune response in chronic hepatitis C infection. This is evidenced by an elevation in serum immunoglobulin isotypes; IgG and its subclasses IgG1 and IgG2 and IgM. These findings may provide some new insights into the antibody response to HCV.

Adult↗