title: Anti-nuclear antibody detection in cryoprecipitates: distinctive patterns in hepatitis C virus-infected patients.
abstract: BACKGROUND
  Anti-nuclear antibodies are immunoglobulins directed against nuclear antigens. They are associated with many autoimmune disorders, but are frequently found in patients infected with hepatitis C virus, possibly indicating an underlying common origin. Likewise, mixed cryoglobulinemia often accompanies autoimmune diseases and hepatitis C infection.
  
  
  OBJECTIVE
  To compare anti-nuclear antibodies and immunoglobulin content of cryoprecipitates from hepatitis C virus-positive patients in order to assess their predictive value in the onset of hepatitis C virus-driven extrahepatic disorders.
  
  
  METHODS
  Serum from 40 hepatitis C virus-positive patients and 50 controls with rheumatoid arthritis was processed for cryoglobulin detection: all subjects presented with Type III mixed cryoglobulinemia. Immunoglobulin content and immunoglobulin subclasses of cryoprecipitates were assessed by immunofixation and tested by ELISA for rheumatoid factor. Cryoprecipitates were also analysed for anti-nuclear antibodies by indirect immuno-fluorescence to identify specific patterns typical of each condition.
  
  
  RESULTS
  Anti-nuclear antibody patterns differed significantly; 26 infected subjects (65%) were IgG3 positive: of these, 25 were also anti-nuclear antibody-positive (96.1%).
  
  
  CONCLUSIONS
  IgG3 are autoreactive clones unrelated to viral recognition and possibly involved in autoimmune disorders. Altogether, these results may represent useful diagnostic device for early detection of hepatitis C virus-induced autoimmune diseases.
authors.affiliation: Department of Laboratory Medicine, Catholic University of the Sacred Heart, Rome, Italy. Electronic address: umberto.basile@rm.unicatt.it.
authors.forename: Umberto
authors.initials: U
authors.lastname: Basile
authors.affiliation: Institute of Internal Medicine, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Gulli
authors.affiliation: Department of Laboratory Medicine, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Torti
authors.affiliation: Institute of Internal Medicine, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: De Matthaeis
authors.affiliation: Institute of Biochemistry, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Colacicco
authors.affiliation: Institute of Microbiology, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Cattani
authors.affiliation: Institute of Internal Medicine, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Gian Lodovico
authors.initials: GL
authors.lastname: Rapaccini
mesh_terms: D000974:Antibodies, Antinuclear / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000276:immunology; D016022:Case-Control Studies; D003449:Cryoglobulinemia / Q000150:complications / Q000276:immunology*; D003450:Cryoglobulins / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016174:Hepacivirus / Q000235:genetics; D006526:Hepatitis C / Q000276:immunology* / Q000821:virology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D007075:Immunoglobulin M / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000235:genetics*; D012217:Rheumatoid Factor / Q000276:immunology
chemical_list: D000974:Antibodies, Antinuclear; D003450:Cryoglobulins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012367:RNA, Viral; D012217:Rheumatoid Factor
keywords: Autoimmune disease; Immunoglobulins; Rheumatoid factor