Cytochromes P-450 in human hepatocyte plasma membrane: recognition by several autoantibodies

Gastroenterology. 1993 Jan;104(1):203-16. doi: 10.1016/0016-5085(93)90853-5.


Background: Anti-cytochrome P-450 autoantibodies are present in several forms of autoimmune hepatitis. The possibility that cytochromes P-450 are present in the plasma membrane of human hepatocytes was examined.

Methods: (1) Plasma membranes with microsomal contamination < 1%, as judged from the activities of glucose-6-phosphatase and NADH-cytochrome c reductase, were prepared. (2) After exposure of uncut, fixed hepatocytes to antibodies, immunofluorescence and immunoperoxidase studies were performed.

Results: (1) The specific content of cytochrome P-450 in plasma membrane was 9% of that in microsomes. Plasma membranes showed NADPH-cytochrome c reductase and mono-oxygenase activities; immunoblots showed the presence of cytochromes P-450 1A2, 2C, 2D6, 2E1, and 3A4; cytochromes P-450 1A2, 2D6, and 2C were also recognized by anti-liver microsome and anti-liver/kidney microsome type 1 and type 2 autoantibodies, respectively. (2) Immunofluorescence and immunoperoxidase labeling of the plasma membrane was observed with the three auto-antibodies and with anti-cytochrome P-450 1A2, 2C, 2E1, or 3A4.

Conclusions: It is concluded that cytochromes P-450 are present and functional in the plasma membrane of human hepatocytes and that anti-cytochrome P-450 autoantibodies recognize epitopes expressed on the outer surface.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autoantibodies / immunology*
  • Cell Membrane / metabolism
  • Cytochrome P-450 Enzyme System / immunology
  • Cytochrome P-450 Enzyme System / metabolism*
  • Epitopes
  • Fluorescent Antibody Technique
  • Hepatectomy
  • Humans
  • Immunoblotting
  • Immunoenzyme Techniques
  • Kidney / immunology
  • Liver / cytology
  • Liver / metabolism*
  • Microsomes / immunology
  • Microsomes, Liver / immunology
  • NADPH-Ferrihemoprotein Reductase / metabolism
  • Oxygenases / metabolism
  • Perfusion


  • Autoantibodies
  • Epitopes
  • Cytochrome P-450 Enzyme System
  • Oxygenases
  • NADPH-Ferrihemoprotein Reductase