The Major Histocompatibility Complex
and Antigen Presentation
The Structure and Function of MHC Class I and II
Molecules
Class II Molecules Consist of Two Nonidentical
Membrane-Bound Glycoprotein Chains
Class I Molecules Consist of One Large Glycoprotein
Heavy Chain Plus a Small Protein Light Chain
Class I and II Molecules Exhibit Polymorphism in
the Region That Binds to Peptides
Class I Molecules Consist of One Large Glycoprotein
Heavy Chain Plus a Small Protein Light Chain
The Organization and Inheritance of MHC Genes
MHC Molecules Are Codominantly Expressed
Class I and Class II Molecules Exhibit Diversity at
Both the Individual and Species Levels
Allelic Forms of MHC Genes Are Inherited in Linked
Groups Called Haplotypes
MHC Polymorphism Is Primarily Limited to the
Antigen-Binding Groove 550
The MHC Locus Encodes the Three Major Classes of
MHC Molecules
The Role and Expression Pattern of MHC Molecules
MHC Expression Can Change with Changing
Conditions
MHC Alleles Play a Critical Role in Immune
Responsiveness
Expression of MHC Class II Molecules Is Primarily
Restricted to Antigen-Presenting Cells
Seminal Studies Demonstrate That T Cells
Recognize Peptide Presented in the Context of SelfMHC Alleles
MHC Class I Expression Is Found Throughout the
Body
Evidence Suggests Distinct Antigen Processing and
Presentation Pathways
MHC Molecules Present Both Intracellular and
Extracellular Antigens
Viral Interference
Cytokine-Mediated Signaling
Genetic Regulatory Components
The Endogenous Pathway of Antigen Processing
and Presentation
Peptides Are Transported from the Cytosol to the
Rough Endoplasmic Reticulum
Chaperones Aid Peptide Assembly with MHC Class I
Molecules
Peptides Are Generated by Protease Complexes
Called Proteasomes
The Exogenous Pathway of Antigen Processing and
Presentation
Peptides Are Generated from Internalized Antigens
in Endocytic Vesicles
The Invariant Chain Guides Transport of MHC Class
II Molecules to Endocytic Vesicles
Peptides Assemble with MHC Class II Molecules by
Displacing CLIP
Unconventional Antigen Processing and
Presentation
Cross-Presentation by APCs Is Essential for the
Activation of naïve CD8 T Cells
Dendritic Cells Can Cross-Present Exogenous
Antigen via MHC Class I Molecules
Presentation of Nonpeptide Antigens