Detection of anti-LKM-1(anti-CYP2D6) by an enzyme-linked immunosorbent assay in adult patients with chronic liver diseases

Anti-liver kidney microsome-1 (LKM-1) autoantibody, which is a serological marker for autoimmune hepatitis type II, recognizes Cytochrome P450 IID6 (C YP2D6), This autoantibody is also detected in a portion of patients with ch ronic hepatitis C, Anti-LKM-1 has been measured by indirect immunofluoresce nce (IF) using rat liver and kidney sections. However, this method has some problems in specificity and is so laborious to handle with many samples. I n this study, in order to determine anti-LKM-1, we established an enzyme-li nked immunosorbent assay (ELISA) for anti-CYP2D6 using a recombinant CYP2D6 fusion protein. We studied sera from 29 patients positive for anti-LKM-1 b y the new ELISA, We further studied sera from a total of 301 patients with various liver diseases and 100 sera from normal controls negative for anti- LKM-1 by the new ELISA. The specificity of the ELISA,vas ascertained by abs orption tests using sera positive for anti-LKM-1, In 29 sera from patients positive for anti-LKM-1 by IF, we found a good correlation between the loga rithms of the antibody titers determined by IF and ELISA indexes obtained b y our new method. Anti-CYP2D6 was positive in 12 of 12 (100%) patient with autoimmune hepatitis type II and 16 of 17 (94.1%) with chronic hepatitis C positive for anti-LKM-1 by IF. In other 401 sera negative for anti-LKM-1 by IF, anti-CYP2D6 was all negative except a few sera. We established a new E LISA for anti-LKM-1 (anti-CYP2D6). This ELISA system is sensitive, antigen- specific and easy to be done. Therefore, this assay allows a routine test o f many serum samples, especially for diagnosing autoimmune hepatitis type I I.