A NEW APPROACH TO CYTOCHROME CYP2D6 ANTIBODY DETECTION IN AUTOIMMUNE HEPATITIS TYPE-2 (AIH-2) AND CHRONIC HEPATITIS-C VIRUS (HCV) INFECTION- A SENSITIVE AND QUANTITATIVE RADIOLIGAND ASSAY

Antibodies specific for cytochrome CYP2D6, formally known as liver-kid ney-microsome type-1 antibodies (LKM-1), are characteristically found in a subgroup of patients presenting autoimmune hepatitis. They are al so found in some patients with chronic HCV infection. These autoantibo dies are usually detected by indirect immunofluorescence, immunoblotti ng and ELISA tests. In an attempt to set up a more sensitive detection assay we developed a quantitative immunoprecipitation radioligand ass ay using a S-35-methionine-labelled CYP2D6 antigen obtained by in vitr o transcription and translation synthesis. All 16 sera from AIH-2 pati ents strongly bound to this CYP2D6 antigen. Two of the nine sera (22%) from AIH-2 patients that presented only liver cytosol-l antibodies al so bound to CYP2D6. All 24 sera from HCV patients that were positive f or LKM-1 antibodies by indirect immunofluorescence were also positive using this CYP2D6 radioligand assay. Lastly, all 15 sera from HCV pati ents negative for LKM-1 antibodies were negative by this test. The pre sent results support the view that this quantitative radioligand assay is more sensitive than immunoblotting and ELISA CYP2D6 assays, and th at it could be used in combination with indirect immunofluorescence as say.