Monoclonal antibody against tumour‐derived cell line shows heterogeneity of altered hepatocytes during afb1‐induced carcinogenesis

Abstract

Monoclonal antibodies have been raised against a tumour cell line (JBI) derived from an aflatoxin B₁-fed rat liver. One antibody MRC TU/Jl has been characterized in terms of its immunohistochemical staining in sections of control and AFB,-fed liver and by the proteins which it immunoprecipitated. The antibody reacted with bile duct epithelium in all sections. In control liver sections there was staining of hepatocyte membranes, with increased stain in periportal regions in animals ⩾12 weeks old. In AFB,-fed liver sections, areas of biliary hyperplasia were stained and after 4 weeks on AFB₁-diet, foci of altered hepatocytes were visible. These were negative, positive or heterogeneous with respect to antibody stain. The antibody reacted much more strongly with adenomatous and cholangiomatous tissue compared with trabecular regions of hepatic tumours which developed in animals after 14 weeks on AFB, diet and 9 months on control diet. After immunoprecipitation of ¹⁴C-leucine-labelled proteins from a JBI cell lysate by MRC TU/Jl, 5 bands in the molecular weight range 43,000-49,000 daltons were visualized on 10% SDS-PAGE gels. A similar result was obtained with ¹⁴C-glucosamine in place of leucine, indicating that all 5 bands were glycoproteins. Deglycosylation of JBI cell lysates with CNBH₁-/IO₄- prevented immunoprecipitation of all bands, suggesting that MRC TU/JI recognized antigenic sites on the carbohydrate portions of the molecules.