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

Abstract

SUMMARYSeveral subtypes of anti-liver-kidney microsome antibodies (LKM) are known, LKM-1 antibodies associated with autoimmune chronic active hepatitis recognize P450 2Df). aeytochrome P450mono-oxygenase. The frequent association of anti-LKM-I antibodies and hepatitis C virus (HCV) infections and the probable existence of an infectious and autoimmune form of anti-LKM-lassociated hepatitis, requiring different therapeutical strategies, necessitates the exact determination of anti-LKM-1 specificities. Therefore, we compared various antibody tests (immunofluorescence. ELISA witb recombinant P450 2D6. and Western bloi with rccombinani and natural antigens and agargel double diffusion) with sera of 27 anti-LKM-1-positive chronic active hepatitis (CAH) patients, with 61 sera harbouring anti-mitoehondriai antibodies. !()() sera each from HCV-RNApositive and HCV-RNA-ncgative patients, and 50 sera of healtby persons. Western blot techniques using recombinant MS2-polymcrase P450 2D6 fusion protein were found to be the most sensitive and specific method for anli-LKM-1 antibody determination in routine laboratory. The recently recognized association of anti-LKM-l antibody and HCV infection was confirmed by the results of this study. In anti-HCV and HCV-RNA-positivc patients with anti-LKM-1 antibodies there was a preponderance of males with higher mean age and lower antibody tUres. The results support the hypothesis of the cxistcnee of an autoimmune as well as an infectious (HCV triggered) subgroup of anti-LKM-t-positive hepatitis.

Differences in immune recognition of cytochrome P4502D6 by liver kidney microsomal (LKM) antibody in autoimmune hepatitis and chronic hepatitis C virus infection

“…The demographic characteristics of the HCV-positive patients in our and the other studies are indeed different. While males predominated marginally or substantially in the reports of Manns et al [11], Seelig et al [12] and Yamamoto et al [13] (six of 11, 55%; nine of 11, 82%; and eight of 15, 54%, respectively), females prevail in our study (27 of 37, 73%). This finding has two implications.…”

“…Our data show that reactivity to CYP2D6 is present in 72% of patients with classical LKM-1-positive AMH, but in a signifi- [13]. In contrast, Manns et al [11] and Seelig et al [12] found that LKM-1 positivity was almost invariably associated with CYP2D6 reactivity, irrespective of HCV status. These discrepancies have several possible explanations.…”

“…The observed differences could be accounted for by differences in the titre of LKM-1 antibody in HCV-infected patients in the four studies, which could, in turn, influence the ability to detect antibody to CYP2D6. In three studies [11][12][13] LKM-1 antibody titre was lower in HCV-positive patients, but in two of them [1 1,12] this was not accompanied by a lower frequency of reactivity to CYP2D6. Conversely, in the present study we find that the LKM-1 titre was similar in the two patient groups, while the frequency of CYP2D6 reactivity was significantly lower in the HCV-positive population.…”

“…Whilst Manns et al [11] and Seelig et al [12] found that all LKM-1-positive sera recognize CYP2D6 irrespective of their HCV status, two other reports showed that reactivity to CYP2D6 was significantly less frequent in LKM-lpositive sera from HCV-positive patients [7,13]. To [15].…”

Brazilian society of hepatology recommendations for the diagnosis and management of autoimmune diseases of the liver

“…It reacts with CYP2D6 antigens, but can be positive in up to 5% of hepatitis C patients (23) .As previously pointed out, patients with AIH-2 are younger, have lower levels of gamaglobulin, carry more frequently HLA-DR7 and/or -DQ2 genotypes and are more prone to have FHF at presentation, when compared to their counterparts with AIH-1 (24,25) . Other AA can be tested to better characterize AIH patients without those aforementioned conventional antibodies.…”