Major Histocompatibility Complex

Question 1

Role of MHC in antigen binding of T cell

Answer 1

T cell receptors can only bind MHC-bound antigen

Question 2

What T cell receptors bind

Answer 2

Bind both antigen and MHC molecule

Question 3

MHC class I protein structure

Answer 3

Alpha chain with beta-2 microglobulin bound to it noncovalently
1 amino acid chain

Question 4

What cells have MHC class I on their surfaces?

Answer 4

All nucleated cells of the body

Question 5

MHC class II protein structure

Answer 5

Alpha and beta chains

2 amino acid chains

Question 6

Antigen presenting cells use which MHC class?

Answer 6

MHC class II

Question 7

MHC class I is associated with which pathway?

Answer 7

Endogenous (antigen coming from inside of cell, like virus)

Question 8

MHC class II is associated with which pathway?

Answer 8

Exogenous (antigen coming from outside of cell, like bacteria)

Question 9

Is binding to MHC as specific as binding to a B or T cell receptor?

Answer 9

No- MHC recognizes a wide variety of epitopes

Question 10

3 factors that enable a MHC molecule to recognize a wide variety of epitopes

Answer 10

Polygenic: several genes exist for a given MHC class
Polymorphic: large number of alleles exist for a given gene
Promiscuous: MHC will bind a range of similar epitopes

Question 11

MHC hypermutation sites

Answer 11

MHC has a high rate of mutation in peptide binding cleft- creates ability to present almost every possible antigen

Question 12

Codominant expression of MHC

Answer 12

Both copies of MHC genes are expressed

High number of alleles makes most individuals heterozygous

Question 13

Additional factor that leads to MHC diversity at gene level

Answer 13

MHC has a high rate of recombination

Question 14

Function of MHC class I

Answer 14

Present endogenously produced antigen (virally-infected cells and tumor cells) to CD8 T-cells (T cytotoxic cells)

Question 15

Function of MHC class II

Answer 15

Present exogenously produced antigen (bacteria, etc.) to CD4 T cells (T helper cells)

Question 16

MHC restriction

Answer 16

Given T cell receptor will only recognize antigen presented by a self-MHC molecule