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| *Viral proteins are broken down to peptides by the proteasome and transferred to the endoplasmic reticulum via TAP (Transporters associated with Antigen Processing) molecules | | *Viral proteins are broken down to peptides by the proteasome and transferred to the endoplasmic reticulum via TAP (Transporters associated with Antigen Processing) molecules |
| *In the ER peptides are processed with empty MHC I molecules and exported to the cell surface for presentation | | *In the ER peptides are processed with empty MHC I molecules and exported to the cell surface for presentation |
− | * MHC class I molecules present these to the T-cell receptors of [[Lymphocytes - WikiBlood#Cytotoxic CD8+|'''CD8+ T-cells''']] | + | * MHC class I molecules present these to the T-cell receptors of [[Lymphocytes#Cytotoxic CD8+|'''CD8+ T-cells''']] |
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| ==MHC II== | | ==MHC II== |
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| | | |
| ===Structure=== | | ===Structure=== |
− | * MHC class II is expressed mainly on [[Macrophages - WikiBlood|macrophages]], [[T cell differentiation - WikiBlood#Antigen Presentation by Dendritic Cells|dendritic cells]] and [[Lymphocytes - WikiBlood#B Cells|B-lymphocytes]] | + | * MHC class II is expressed mainly on [[Macrophages - WikiBlood|macrophages]], [[T cell differentiation - WikiBlood#Antigen Presentation by Dendritic Cells|dendritic cells]] and [[Lymphocytes#B Cells|B-lymphocytes]] |
| * MHC class II consists of membrane-associated α and β chains | | * MHC class II consists of membrane-associated α and β chains |
| ** Each chain is a transmembrane glycoprotein | | ** Each chain is a transmembrane glycoprotein |
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| ***The invariant chain is digested, leaving a CLIP peptide in the binding groove | | ***The invariant chain is digested, leaving a CLIP peptide in the binding groove |
| ***Foreign antigen then replaces the CLIP peptide | | ***Foreign antigen then replaces the CLIP peptide |
− | *The MHC II-antigen complex is then secreted to the cell surface for presentation to [[Lymphocytes - WikiBlood#Helper CD4+|CD4+ T-cells]] | + | *The MHC II-antigen complex is then secreted to the cell surface for presentation to [[Lymphocytes#Helper CD4+|CD4+ T-cells]] |
| | | |
| =Interaction of MHC With Antigen= | | =Interaction of MHC With Antigen= |
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| ** 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 [[Lymphocytes - WikiBlood#T Cells|T cell]] receptor recognition | + | *** Is the target for [[Lymphocytes#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 |
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| ==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 [[Lymphocytes - WikiBlood#T Cells|T cells]] | + | * Only peptide associated with self-MHC will interact with and activate [[Lymphocytes#T Cells|T cells]] |
− | ** [[Lymphocytes - WikiBlood#T Cells|T cells]] cannot be activated by a peptide on a foreign cell | + | ** [[Lymphocytes#T Cells|T cells]] cannot be activated by a peptide on a foreign cell |
− | ** [[Lymphocytes - WikiBlood#T Cells|T cells]] will react against foreign MHC molecules | + | ** [[Lymphocytes#T Cells|T cells]] will react against foreign MHC molecules |
| *** This is the basis of graft rejection | | *** This is the basis of graft rejection |
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