title: Membranoproliferative glomerulonephritis associated with hepatitis C virus infection.
abstract: METHODS
  Hepatitis C virus (HCV) infection causes both acute and chronic liver disease and is also associated with mixed cryoglobulinemia. Whether HCV is also associated with renal disease, as is the hepatitis B virus, is not known. We describe the clinical, pathologic, virologic, and immunologic features of eight patients with HCV infection who were referred to nephrologists for glomerulonephritis. Four patients were treated with interferon alfa.
  
  
  RESULTS
  All eight patients had proteinuria, and seven had decreased renal function. Renal biopsy in all patients revealed membranoproliferative glomerulonephritis, characterized by the deposition of IgG, IgM, and C3 in glomeruli. Electron microscopy of the biopsy specimens showed cryoglobulin-like structures in three of four patients. All eight patients had HCV RNA detected in their serum, elevated serum aminotransferase concentrations, and hypocomplementemia, and the majority had cryoglobulins and circulating immune complexes in their serum. Cryoprecipitates from the three patients who were tested contained HCV RNA and IgG anti-HCV antibodies to the nucleocapsid core antigen (HCVc or c22-3). IgM rheumatoid factors, present in all patients, bound anti-HCV IgG in all six patients tested. Four patients received interferon alfa for 2 to 12 months; all had evidence of decreased HCV replication and improvement of their renal and liver disease.
  
  
  CONCLUSIONS
  Chronic HCV infection is associated with cryoglobulinemia and membranoproliferative glomerulonephritis. The pathogenesis is unknown, but may relate to deposition within glomeruli of immune complexes containing HCV, anti-HCV IgG, and IgM rheumatoid factors.
authors.affiliation: Department of Medicine, University of Washington Medical Center, Seattle 98195.
authors.forename: R J
authors.initials: RJ
authors.lastname: Johnson
authors.forename: D R
authors.initials: DR
authors.lastname: Gretch
authors.forename: H
authors.initials: H
authors.lastname: Yamabe
authors.forename: J
authors.initials: J
authors.lastname: Hart
authors.forename: C E
authors.initials: CE
authors.lastname: Bacchi
authors.forename: P
authors.initials: P
authors.lastname: Hartwell
authors.forename: W G
authors.initials: WG
authors.lastname: Couser
authors.forename: L
authors.initials: L
authors.lastname: Corey
authors.forename: M H
authors.initials: MH
authors.lastname: Wener
authors.forename: C E
authors.initials: CE
authors.lastname: Alpers
mesh_terms: D000328:Adult; D000368:Aged; D000936:Antigen-Antibody Complex / Q000097:blood; D003176:Complement C3 / Q000032:analysis; D003449:Cryoglobulinemia / Q000209:etiology; D005260:Female; D015432:Glomerulonephritis, Membranoproliferative / Q000209:etiology* / Q000276:immunology / Q000473:pathology; D016174:Hepacivirus / Q000276:immunology; D006508:Hepatitis Antibodies; D006526:Hepatitis C / Q000150:complications* / Q000276:immunology / Q000628:therapy; D018937:Hepatitis C Antibodies; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D016898:Interferon-alpha / Q000627:therapeutic use; D007668:Kidney / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000209:etiology; D012367:RNA, Viral / Q000032:analysis
chemical_list: D000936:Antigen-Antibody Complex; D003176:Complement C3; D006508:Hepatitis Antibodies; D018937:Hepatitis C Antibodies; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D016898:Interferon-alpha; D012367:RNA, Viral