MHC Structure and Function

Question 1

What is the major histocompatibility complex?

Answer 1

Human leukocyte antigen

Presents a peptide derived from the invading organism

These HLA molecules interact with the TCR of a helper, cytotoxic, or suppressor T cell

Question 2

What is difference between class I MHC and class 2?

Answer 2

Class I - Expressed on all cells in the body

Class II - activation molecule, restricted expression to APCs

Question 3

How are the alleles for the MHC genes expressed?

Answer 3

Coexpression

Both the maternal and paternal alleles are expressed for each MHC complex

Question 4

What does the MHC Class III gene encode?

Answer 4

Encodes Tap and complement proteins

No structural genes

Question 5

What three types of cells can process and present antigen?

Answer 5

Dendritic cells

Macrophages

B cells

Question 6

What is the responsibility of each MHC class molecule on APCs?

Answer 6

MHC class I - binds peptides from intracellular pathogens and presents to CD8 T cell (cytotoxic)

MHC class II - binds extracellular pathogen and presents to CD4 T cell (helper)

Question 7

What is MHC restriction?

Answer 7

T cell receptor binds to both the peptide and the MHC molecule

Means both the peptide and MHC have to match the receptor on the T cell

Question 8

What is the significance of individuals in a population being mostly heterozygotes for MHC molecule alleles?

Answer 8

Ensures a broader spectrum of peptides that can be bound by any one individual

Question 9

Where are polymorphisms found in MHC molecules?

Answer 9

Regions that determine which peptides can be bound