Heterogeneity of liver-kidney microsomal autoantibodies in chronic hepatitis C and D virus infection.
OBJECTIVE
Anti-liver-kidney microsomal (LKM) autoantibodies occur in a proportion of patients with chronic hepatitis C and D infections. Because of different immunofluorescence patterns, antibodies in hepatitis C and D were termed LKM-1 and LKM-3, respectively. The aim of the present study was to evaluate the different specificities of LKM-1 and LKM-3 antibodies.


METHODS
Forty-nine samples of LKM-1 sera and 16 samples of LKM-3 sera were studied for reactivity against rat and human liver microsomal proteins by immunofluorescence, enzyme-linked immunosorbent assay, and Western blot.


RESULTS
Thirty-four percent of the LKM-1 sera reacted with 50-kilodalton cytochrome P4502D6 in Western blot. In addition, a proportion of the sera recognized either a 59- or 70-kilodalton antigen, and 45% of the sera did not react in Western blot. Recently, the major LKM-3 antigen was identified as an autoepitope expressed on uridine diphosphate-glucuronosyltransferases (UGT). Seven LKM-3-positive sera reacted with recombinant rabbit family one UGT. None of the anti-LKM-1-positive hepatitis C sera reacted with UGT. Antibody reactivity against liver microsomal proteins in enzyme-linked immunosorbent assay ended when antigens were pretreated with sodium dodecyl sulfate, confirming that antibodies recognize conformational epitopes.


CONCLUSIONS
LKM-1 antibodies in hepatitis C are more heterogeneous and react with different antigens compared with LKM-3 antibodies in hepatitis D.
Medizinische Hochschule Hannover, Abteilung Gastroenterologie und Hepatologie, Germany.
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Durazzo
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Philipp
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Van Pelt
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B
Lüttig
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Borghesio
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Michel
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Schmidt
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Loges
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Rizzetto
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Manns
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000097:blood; D000918:Antibody Specificity; D001323:Autoantibodies / Q000097:blood*; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006526:Hepatitis C / Q000097:blood / Q000276:immunology*; D003699:Hepatitis D / Q000097:blood / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D051381:Rats
D000888:Antibodies, Anti-Idiotypic; D001323:Autoantibodies; D007074:Immunoglobulin G; C060729:anti-liver kidney microsome antibody