MHC class I antigen expression and alterations induced by rIFN gamma in tumor hybrid cell immunogenicity

Hybridization of a poorly immunogenic tumor cell with an allogeneic cell was performed in order to improve tumor immune response; several variants derived from one hybrid tumor cell were studied. We compared the immunogenicity of these variants and their allogeneic and syngeneic class I antigen expression before and after IFN gamma treatment. Allogeneic class I antigens were weakly expressed in all variants; IFN treatment enhanced their expression similarly in both immunogenic and nonimmunogenic variants. Syngeneic class I antigen expression differed among variants: IFN treatment induced changes in their expression which corresponded to a posttranscriptional event and which could, at least partly, explain the modifications observed in their immunogenicity.