Changes

==TCR-MHC Interaction==

==TCR-MHC Interaction==

[[Image:MHC T cell Interaction.jpg|thumb|right|200px|Molecules of T lymphocyte recognition - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]

[[Image:MHC T cell Interaction.jpg|thumb|right|200px|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]], which cannot be activated by a peptide on a foreign cell.

Only peptide associated with MHC will interact with and activate [[T cells]]. T cells therefore cannot be directly activated by a peptide on a foreign organism.

T cells will react against foreign MHC molecules and this is the basis of graft rejection

T cells will react against foreign MHC molecules and this is the basis of graft rejection