title: Hepatitis C virus infection in patients with essential mixed cryoglobulinemia.
abstract: OBJECTIVE
  To study the association between hepatitis C virus (HCV) infection and essential mixed cryoglobulinemia.
  
  
  METHODS
  Wards and clinics of the Ospedali Riuniti di Bergamo and Ospedale di Treviglio e Caravaggio, Italy.
  
  
  METHODS
  Fifty-one patients with essential mixed cryoglobulinemia associated with glomerulonephritis and 45 controls with noncryoglobulinemic glomerulopathies.
  
  
  METHODS
  Antibodies to hepatitis C virus (anti-HCV) in sera from patients with essential mixed cryoglobulinemia and from controls, using two enzyme-linked immunosorbent assays (c100 ELISA and c22/c200 ELISA) and a recombinant immunoblot assay (4-RIBA); cryoprecipitate anti-HCV before and after use of dithiothreitol, a substance able to destroy IgM antibodies with rheumatoid factor activity, in patients with essential mixed cryoglobulinemia; serum HCV RNA by polymerase chain reaction in patients with essential mixed cryoglobulinemia.
  
  
  RESULTS
  In patients with essential mixed cryoglobulinemia, the c22/c200 ELISA detected anti-HCV in 98% of serum samples (95% CI, 90% to 100%), whereas the rate of reactivity remained at 2% (CI, 0% to 12%) in the control group (P less than 0.0001). These results were confirmed by the 4-RIBA in 66% of patients with essential mixed cryoglobulinemia. The study of cryoprecipitate by c100 ELISA showed anti-HCV in 41% (Cl, 28% to 56%) of patients. After dithiothreitol, the rate of reactivity increased to 94% (CI, 84% to 99%; P less than 0.0001 by the McNemar paired chi-square test), suggesting that the elimination of rheumatoid factor leads to unmasking of anti-HCV in cryoprecipitate. Polymerase chain reaction detected HCV RNA in 13 of 16 sera from patients with essential mixed cryoglobulinemia.
  
  
  CONCLUSIONS
  The extremely high prevalence of anti-HCV in serum and cryoprecipitate along with the frequently associated serum HCV RNA suggests a close relation between essential mixed cryoglobulinemia and chronic HCV infection.
authors.affiliation: Ospedali Riuniti di Bergamo, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Misiani
authors.forename: P
authors.initials: P
authors.lastname: Bellavita
authors.forename: D
authors.initials: D
authors.lastname: Fenili
authors.forename: G
authors.initials: G
authors.lastname: Borelli
authors.forename: D
authors.initials: D
authors.lastname: Marchesi
authors.forename: M
authors.initials: M
authors.lastname: Massazza
authors.forename: G
authors.initials: G
authors.lastname: Vendramin
authors.forename: B
authors.initials: B
authors.lastname: Comotti
authors.forename: E
authors.initials: E
authors.lastname: Tanzi
authors.forename: G
authors.initials: G
authors.lastname: Scudeller
mesh_terms: D001483:Base Sequence; D003449:Cryoglobulinemia / Q000150:complications* / Q000382:microbiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016174:Hepacivirus / Q000302:isolation & purification; D006508:Hepatitis Antibodies / Q000097:blood; D006526:Hepatitis C / Q000150:complications* / Q000276:immunology; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000097:blood
chemical_list: D006508:Hepatitis Antibodies; D012367:RNA, Viral