8 Questions
Which type of T cells can respond only to peptides displayed by class I MHC molecules?
CD8+ T cells
Which domains of class II MHC molecules contain the binding site for the CD4 T cell coreceptor?
α2 and β2 domains
What is the function of the α3 domain of class I MHC molecules?
Binds CD8 T cell coreceptor
What does the polymorphism of MHC genes refer to?
Variability in alleles among individuals in the population
What makes MHC molecules the most polymorphic of all proteins in mammals?
They are inherited and not generated de novo by somatic gene recombination
How many alleles of each MHC gene does an individual inherit and express?
Two
What is the role of MHC polymorphism in dealing with the diversity of microbes?
Ensuring some members of the population can present peptides from any microbial protein antigen
Why does the existence of many different MHC molecules in the population prevent everyone from succumbing to newly encountered or mutated microbes?
By ensuring at least some individuals can mount effective immune responses to peptide antigens
Study Notes
MHC Molecules and T Cells
- CD8 T cells can respond only to peptides displayed by class I MHC molecules
- The binding site for the CD4 T cell coreceptor is located in the β2 domain of class II MHC molecules
- The α3 domain of class I MHC molecules serves as a binding site for CD8
MHC Polymorphism
- MHC gene polymorphism refers to the existence of multiple alleles of each MHC gene in the population
- MHC molecules are the most polymorphic of all proteins in mammals due to the large number of alleles and their high degree of variability
- An individual inherits and expresses two alleles of each MHC gene, one from each parent
Role of MHC Polymorphism in Immunity
- MHC polymorphism allows individuals to respond to a diverse range of microbes
- The existence of many different MHC molecules in the population prevents everyone from succumbing to newly encountered or mutated microbes
- This is because a pathogen that can evade the immune system of one individual may be targeted by the MHC molecules of another individual
Test your knowledge on Major Histocompatibility Complex (MHC) molecules and T cell activation. This quiz covers the α3 domain, β2-microglobulin, CD8 T cell coreceptor, CD4, class I MHC molecules, and class II MHC molecules.
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