MHC and Tissue Compatibility Quiz

Antigen Recognition and MHC Molecules

• CD8+ T cells recognize peptide antigens displayed by MHC class I molecules
• MHC molecules play a physiological role in presenting antigens to T-cells for recognition and response

MHC and Graft Acceptance

• Identical twins are likely to accept grafts from each other due to their identical MHC makeup

Human Leukocyte Antigens (HLAs)

• HLA genes are highly polymorphic, with many alleles, causing different individuals to have distinct HLA types
• HLA genes are responsible for encoding MHC molecules

MHC Genes and Proteins

• Class I MHC genes encode proteins that present endogenous antigens to CD8+ T cells
• Class II MHC genes encode proteins that present exogenous antigens to CD4+ T cells
• The polymorphism of MHC genes refers to the high degree of genetic variation between individuals

Class I MHC Structure and Function

• The alpha 1 and alpha 2 domains of class I MHC molecules contain polymorphic residues
• The CD8 T cell coreceptor binds to the alpha 3 domain of class I MHC molecules
• The peptide-binding cleft of class I MHC molecules can accommodate peptides typically 8-11 amino acids in length
• The CD8 coreceptor functions to stabilize the interaction between the T cell receptor and the MHC-peptide complex during T cell activation

Class II MHC Structure and Function

• The α1 and α2 domains of class II MHC molecules are involved in peptide binding
• The β2-microglobulin is a protein that associates with the α chain of class I MHC molecules to form a functional complex