And once they are bound, the cytotoxic T cell basically does the same exact thing that the natural killer cell does. It releases these digestive proteins that poke holes in the membrane and lice and destroy that cell. So these are the two different types of white blood cells that make up the immunosurveillance system of our bodies. So this is the system by which these white blood cells are continually trying to find these abnormal cells of our bodies, such as cancer cells, as well as our infected cells that might be infected by some type of outside pathogen. So the major difference between our natural killer cell and our cytotoxic T cell is the cytotoxic T cell only binds to the MHC class One complex, while our natural killer cell can bind to a cell that doesn't have that MHC class One complex. And that's very important because sometimes these infected or cancer cells lose the ability to create these complexes that hold the antigens.