Figure 1.

Overcoming the major histocompatibility class I complex

(A–C) The MHC class I functions to identify body cells as belonging to self. Cells that belong to self (A) are recognized as such by immune cells and are left alone. Cells of host origin including infected body cells (B) are recognized as immunologically foreign by cytotoxic T cells and targeted for removal. Removal of the MHC class I by genetic deletion (C) activates natural killer cells that target the cells for removal by lysis.