Anti-LKM-1 is used for the quantitative determination of IgG antibodies to cytochrome P450 IID6 in human serum or plasma. Anti-LKM-1 is an enzyme immunoassay for the quantitative determination of IgG antibodies to cytochrome P450 IID6. The antibodies of the standards, controls, and diluted patient samples react with human recombinant cytochrome P450 IID6 immobilized on the solid phase of microtiter plates. The use of highly purified human recombinant cytochrome P450 IID6 guarantees the specific binding of LKM-1 antibodies of the specimen under investigation. Following an incubation period of 30 min at room temperature (RT), unbound serum components are removed by a wash step. The bound IgG antibodies react specifically with anti-human-IgG conjugated to horseradish peroxidase (HRP) within the incubation period of 30 min at RT. Excessive conjugate is separated from the solid-phase immune complexes by the following wash step. HRP converts the colorless substrate solution of 3,3',5,5'-tetramethylbenzidine (TMB) added into a blue product. The enzyme reaction is stopped by dispensing an acidic solution (HCl) into the wells after 30 min at RT turning the solution from blue to yellow. The optical density (OD) of the solution at 450nm is directly proportional to the amount of specific antibodies bound. The standard curve is established by plotting the antibody concentrations of the standards (x-axis) and their corresponding OD values (y-axis) measured. The concentration of antibodies of the specimen is directly read off the standard curve.