Changes

** These MHC amino acids associate with amino acids near the ends of the peptides

** These MHC amino acids associate with amino acids near the ends of the peptides

*** The intervening stretch of peptide folds into a helix within the groove

*** The intervening stretch of peptide folds into a helix within the groove

*** Is the target for T cell receptor recognition

*** Is the target for [[Lymphocytes - WikiBlood#T Cells|T cell]] receptor recognition

*MHC molecules have the capacity to bind to trillions of different peptides

*MHC molecules have the capacity to bind to trillions of different peptides

**Adopt a flexible '''floppy''' conformation until a peptide binds

**Adopt a flexible '''floppy''' conformation until a peptide binds

==TCR-MHC Interaction==

==TCR-MHC Interaction==

[[Image:MHC T cell Interaction.jpg|thumb|right|150px|Molecules of T lymphocyte recognition - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]

[[Image:MHC T cell Interaction.jpg|thumb|right|150px|Molecules of T lymphocyte recognition - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]

* Only peptide associated with self-MHC will interact with and activate T-cells

* Only peptide associated with self-MHC will interact with and activate [[Lymphocytes - WikiBlood#T Cells|T cells]]

** T-cells cannot be activated by a peptide on a foreign cell

** [[Lymphocytes - WikiBlood#T Cells|T cells]] cannot be activated by a peptide on a foreign cell

** T-cells will react against foreign MHC molecules

** [[Lymphocytes - WikiBlood#T Cells|T cells]] will react against foreign MHC molecules

*** This is the basis of graft rejection

*** This is the basis of graft rejection