An enzyme-linked immunosorbent assay for the detection of hepatocyte plasma membrane antibodies

An enzyme-linked immunosorbent assay (ELISA) using plates coated with hepatocyte plasma membranes (HPM) was developed for the measurement of antibodies directed at hepatocyte surface antigens. Precoating ELISA plates with poly-L-lysine (PLL) provided firm attachment for the adsorption of HPM. The use of HPM, in preference to whole hepatocytes, excludes pathologically irrelevant cytoplasmic antigens. In addition, there is no necessity for glutaraldehyde fixation which is commonly used in cellular assays to maintain cellular integrity and which may result in loss or alteration in antigenic specificities. The assay was used to study loss of tolerance to mouse HPM in mice immunized with rat HPM. Three mouse strains were immunized, each strain developed antibodies to rat HPM and autoantibodies to mouse HPM with autoantibody levels reaching a peak 6-10 weeks after commencement of immunization. The correlation between ELISA and indirect immunofluorescence for the measurement of HPM autoantibodies was 0.79 (P less than 0.001) within the serum titration range of 1:25 to 1:200. Antibody to control kidney plasma membrane (KPM) was also measured by ELISA, after elimination of endogenous alkaline phosphatase activity using levamisole. Immunization with rat HPM elicited organ-non-specific autoantibodies to KPM, but these were at lower levels than autoantibodies to HPM.