Re-expression of major histocompatibility complex (MHC) class I molecules on malignant tumor cells and its effect on host-tumor interaction.

The expression of products encoded by the major histocompatibility complex (MHC) on tumor cells has recently been studied extensively. It has been found that many malignant tumor cells have their MHC antigens 'switched-off' but that these antigens are re-expressed following DNA-mediated gene transfer, with increased tumor immunogenicity as a result and the consequence that these 'transformed' tumor cells are rejected in vivo. This review will discuss approaches that have been taken to induce strong tumor-specific immunity by the manipulation of MHC expression on tumor cells.