Detection of circulating autoantibodies directed against the asialoglycoprotein receptor using recombinant receptor subunit H1.
OBJECTIVE
The asialoglycoprotein-receptor (ASGPR) is a major liver-specific target autoantigen in autoimmune hepatitis. ASGPR heteromers of two subunits H1 and H2 provide clearance of circulating asialoglycoproteins by receptor-mediated endocytosis. The aim of this study was to establish whether a recombinantly expressed subunit H1 presenting conformational epitopes is capable of detecting autoantibodies against ASGPR in patients with inflammatory liver disease.


METHODS
The major subunit H1 was expressed in human-embryo-kidney 293-cells and prepared by ligand-affinity-chromatography similar to the complete receptor from normal liver. Reactivities of anti-ASGPR positive sera from 219 patients with both recombinant H1 and natural receptor were compared using enzyme-immunoassay (EIA).


RESULTS
194 of 219 sera (88.6%) showed absorbance values on 293-H1 within a range of +/-15% compared to the natural receptor. 145 of 149 sera (97.3%) positive on ASGPR were also positive on recombinant H1. Titers of 61/62 sera (98.4%) revealed no deviation of more than one dilution step. ASGPR reactivity could be inhibited in 29 sera with up to 50 ng/microl of 293-H1.


CONCLUSIONS
These results indicate that the antigenic sites of the human ASGPR are mainly located on the mammalian-expressed subunit H1. Therefore, 293-H1 is a powerful tool for the detection of autoantibodies against ASGPR.
Schreiter
Thomas
T
Department of Gastroenterology and Hepatology, University Hospital Essen, Hufelandstr. 55, 45122 Essen, Germany.
Liu
Chao
C
Gerken
Guido
G
Treichel
Ulrich
U
D000941:Antigens / Q000276:immunology; D037263:Asialoglycoprotein Receptor / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology*; D002460:Cell Line; D000939:Epitopes / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D021122:Protein Subunits / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology*; D005719:gamma-Globulins / Q000276:immunology
D000941:Antigens; D037263:Asialoglycoprotein Receptor; D001323:Autoantibodies; D000939:Epitopes; D021122:Protein Subunits; D011994:Recombinant Proteins; D005719:gamma-Globulins