And what the cell does is it essentially takes a viral protein and it places on this complex here inside the cleft instead of this self antigen. So now we have a pathogenic antigen and antigen that comes from that pathogen, our virus. And now when the leukocyte swims by and notices this pathogenic antigen it will bind to it and initiate a set of different types of immune responses that will ultimately destroy this infected cell. So we see that the major histocompatibility complex, class one is actually responsible for allowing our leukocytes to distinguish our healthy cells from the infected cells of our body. Now, what about the second class? What about MHC Class Two?