Human hepatoma cells expressing HLA class I molecules stimulate primary responses of purified CD8+ T lymphocytes

In the present study, we investigated the ability of major histocompatibility complex (MHC) class-I+ human hepatoma cell lines to induce primary proliferative responses of purified allogeneic CD8+ T lymphocytes. We found that HA22T/VGH and Li7A, but not HepG2 cells induced significant proliferation of CD8+ T cells and that these responses were dependent on class I molecule expression. In blocking experiments carried out to identify the costimulatory signals involved, we found that anti-ICAM1 monoclonal antibodies drastically inhibited CD8+ T-cell proliferative responses. These findings suggest that transformed hepatocytes expressing HLA class I molecules may participate in anti-tumour immunosurveillance by the direct induction of cytotoxic T-cell responses through ICAM1-mediated adhesive interaction.