Patients with type II autoimmune hepatitis express functionally intact cytochrome P-450 db1 that is inhibited by LKM-1 autoantibodies in vitro but not in vivo

Hepatology. 1990 Jul;12(1):127-32. doi: 10.1002/hep.1840120120.


Liver-kidney microsomal-1 autoantibodies characterize a subgroup of autoimmune chronic active hepatitis. The liver antigen of liver-kidney microsomal-1 antibodies has been identified as cytochrome P450 db1, a microsomal enzyme catalyzing the oxidative metabolism of more than 20 drugs, including debrisoquine, sparteine and bufuralol. A genetic polymorphism (debrisoquin-sparteine polymorphism) is responsible for the lack of P450 db1 protein in the livers of 5% to 10% of Caucasians, leading to impaired drug metabolism and a distinct poor metabolizer phenotype. We investigated whether liver-kidney microsomal-1 positive autoimmune chronic active hepatitis patients express functionally intact P450 db1 in their livers. In four patients with liver-kidney microsomal-1 positive chronic active hepatitis, but not in five patients with various liver-kidney microsomal-1 negative liver diseases, the presence of circulating liver-kidney microsomal-1 antibodies was confirmed by immunofluorescence, radioimmunoassay and immunoblotting analysis using recombinant P450 db1. Moreover, only sera from liver-kidney microsomal-1 positive autoimmune chronic active hepatitis patients strongly inhibited the enzymatic activity of P450 db1 in human liver microsomes in vitro. Immunoblotting detected 50-kd P450 db1 protein in liver biopsy specimens from all patients. The in vivo function of P450 db1 was investigated by determining the metabolic ratio for sparteine and its 2-dehydro and 5-dehydro metabolites in 12-hr urine samples after oral administration of sparteine sulfate. In vivo P450 db1-mediated drug metabolism was of the extensive metabolizer phenotype and did not differ significantly between liver-kidney microsomal-1 positive (metabolic ratio = 1.15 +/- 0.32) and liver-kidney microsomal-1 negative (metabolic ratio = 1.18 +/- 0.48) patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Autoantibodies / analysis*
  • Autoimmune Diseases / metabolism*
  • Cytochrome P-450 Enzyme Inhibitors
  • Cytochrome P-450 Enzyme System / immunology*
  • Cytochrome P-450 Enzyme System / metabolism
  • Female
  • Humans
  • Immunoblotting
  • Kinetics
  • Liver Cirrhosis / immunology*
  • Liver Cirrhosis / metabolism
  • Male
  • Microsomes, Liver / metabolism*
  • Middle Aged
  • Sparteine / metabolism


  • Autoantibodies
  • Cytochrome P-450 Enzyme Inhibitors
  • anti-liver kidney microsome antibody
  • Sparteine
  • Cytochrome P-450 Enzyme System