Anti-LC1 autoantibodies in patients with chronic hepatitis C virus infection.
Various autoantibodies have been reported in patients chronically infected by hepatitis C virus. 2% to 10% of theses patients have anti-liver-kidney microsome type 1 (anti-LKM1) autoantibodies. In type 2 autoimmune hepatitis, anti-LKM1 autoantibodies are frequently associated with anti-liver-cytosol type 1 (anti-LC1) autoantibodies.


OBJECTIVE
To determine the prevalence of anti-LC1 autoantibodies in a hepatitis C-positive population and characterize their reactivity.


METHODS
146 patients suffering from liver diseases, of which 99 were chronically infected by hepatitis C virus, were tested by Western blotting and immunoprecipitation to detect and characterize anti-LC1 autoantibodies.


RESULTS
12% of this hepatitis C population had anti-LC1 autoantibodies. LC1 positivity by Western blotting was 30% of LC1+ sera. Epitopes were found throughout the protein but linear epitopes were situated in the 395-541 amino acid region of formiminotransferase cyclodeaminase. Three putative conformational epitopes were identified by phage display.


CONCLUSIONS
Anti-LC1 autoantibodies are as prevalent as anti-LKM1 autoantibodies in patients infected with hepatitis C virus and their production is not dependent of anti-LKM1 autoantibodies formation. Autoantibody reactivity against the anti-LC1 antigen is different in hepatitis C than in type 2 autoimmune hepatitis. Anti-LC1 autoantibodies can now be regarded as a serological marker of autoimmunity in chronic hepatitis C infection.
Service de Gastroentérologie et Nutrition, Hôpital Sainte-Justine, 3175 Côte Ste-Catherine, Montreal, Quebec, Canada H3T 1C5.
Kathie
K
Béland
Pascal
P
Lapierre
Gabriel
G
Marceau
Fernando
F
Alvarez
D000328:Adult; D000642:Ammonia-Lyases / Q000235:genetics / Q000276:immunology; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D001324:Autoantigens / Q000235:genetics / Q000276:immunology*; D002675:Child, Preschool; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics / Q000276:immunology; D018604:Epitope Mapping; D016174:Hepacivirus / Q000276:immunology*; D019698:Hepatitis C, Chronic / Q000097:blood / Q000276:immunology*; D019693:Hepatitis, Autoimmune / Q000097:blood / Q000276:immunology; D006801:Humans; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology
D001323:Autoantibodies; D001324:Autoantigens; D011994:Recombinant Proteins; C060729:anti-liver kidney microsome antibody; C077285:liver cytosol antigen type 1, human; D019389:Cytochrome P-450 CYP2D6; D000642:Ammonia-Lyases; C020148:formiminotetrahydrofolate cyclodeaminase