Preparation of aminoazo dye induced rat hepatoma membrane fractions retaining tumour specific antigen.

Membrane fractions were isolated from homogenates of an aminoazo dye induced rat hepatoma (hepatoma D23) by sucrose density gradient centrifugation in zonal rotors. The membrane fractions retained tumour specific antigenic determinants and exhibited an increased antigenic activity over other subcellular membrane fractions, as defined by their capacity to quantitatively neutralize the membrane immunofluorescence staining of viable hepatoma D23 cells by antibody in tumour immune serum. In contrast, no antigenic activity was found to be associated with purified hepatoma D23 nuclei or nuclear membranes as evaluated by the in vitro antigen assay.The two methods described for the isolation of hepatoma D23 membranes have been developed for the large scale fractionation of tumour homogenates in order that further studies upon the nature and immunogenicity of membrane associated tumour specific antigens may be resolved using defined membrane preparations of increased antigenic activity.