Facilitator Questions

1. MHC I is found in all nucleated cells and presents peptides to CD8 T cells, whereas MHC II is found only in antigen presenting cells (APCs) and presents peptides to CD4 T cells. Describe peptide loading of MHC I.
   
   
2. Describe peptide loading of MHC II.


3. How does cross presentation occur? Why is this useful?


4. Tolerance is a critical phenomenon that ensures that your immune system will not launch an immune response against your own cells. Describe how tolerance is achieved both prior to and after birth.