ANTI-LKM-1 ANTIBODIES DETERMINED BY USE OF RECOMBINANT-P450 2D6 IN ELISA AND WESTERN-BLOT AND THEIR ASSOCIATION WITH ANTI-HCV AND HCV-RNA

Several subtypes of anti-liver-kidney microsome antibodies (LKM) are k nown. LKM-1 antibodies associated with autoimmune chronic active hepat itis recognize P450 2D6, a cytochrome P450 monooxygenase. The frequent association of anti-LKM-1 antibodies and hepatitis C virus (HCV) infe ctions and the probable existence of an infectious and autoimmune form of anti-LKM-1-associated hepatitis, requiring different therapeutical strategies, necessitates the exact determination of anti-LKM-1 specif icities. Therefore, we compared various antibody tests (immunofluoresc ence, ELISA with recombinant P450 2D6, and Western blot with recombina nt and natural antigens and agargel double diffusion) with sera of 27 anti-LKM-1-positive chronic active hepatitis (CAH) patients, with 61 s era harbouring anti-mitochondrial antibodies, 100 sera each from HCV-R NA-positive and HCV-RNA-negative patients, and 50 sera of healthy pers ons. Western blot techniques using recombinant MS2-polymerase P450 2D6 fusion protein were found to be the most sensitive and specific metho d for anti-LKM-1 antibody determination in routine laboratory. The rec ently recognized association of anti-LKM-1 antibody and HCV infection was confirmed by the results of this study. In anti-HCV and HCV-RNA-po sitive patients with anti-LKM-1 antibodies there was a preponderance o f males with higher mean age and lower antibody titres. The results su pport the hypothesis of the existence of an autoimmune as well as an i nfectious (HCV triggered) subgroup of anti-LKM-1-positive hepatitis.