Abstract
A subgroup of children with autoimmune hepatitis is defined by the presence in the serum of high titers of LKMA, usually detected by immunofluorescence (IF). We have studied the sera of 5 such children to characterize the antigen recognized by LKMA. Negative controls were provided by sera from children with smooth muscle antibody positive chronic hepatitis, Wilson's disease and Hepatitis B related chronic active hepatitis. Cell fractionation of rat liver and immunoblot analysis showed the antigen to be a protein of 50000 molecular weight, present in high concentrations in smooth microsome subfractions, integrated in the microsomal membranes, and exposed on their cytoplasmic side; the antigen is not glycosylated and does not form homo or heteropolymers by disulfide bonds. Immunoelectronmicroscopy of rat liver showed the antigen to be detectable only in endoplasmic reticulum membranes of hepatocytes and not in other liver cell types. Cell fractionation and immunoblot of human liver detected a 48000 MW protein with characteristics similar to that of rat liver. An ELISA technique was developed, using rat liver microsomes as substrate, that proved to be most useful for diagnosis and follow-up studies, being more sensitive and cheaper than IF. These results may prove useful both for improving detection and care of these children and for understanding the mechanisms of autoimmune hepatitis.
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Alvarez, F., Delemos-Chiarandini, C., Paradis, K. et al. 3. CHARACTERIZATION OF THE ANTIGEN RECOGNIZED BY THE ANTI-LIVER KIDNEY MICROSOME ANTIBODIES (LKMA). Pediatr Res 22, 96 (1987). https://doi.org/10.1203/00006450-198707000-00024
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DOI: https://doi.org/10.1203/00006450-198707000-00024