MHC Molecules and Antigen Presentation

Question 1

pMHC

Answer 1

MHC with peptide bound

Question 2

The TCR is made up of. . .

Answer 2

One α chain, one β chain

Each contains its own distinct V domain with 3 hypervariable loops (6 total).

Question 3

CD4+ T cells are ___ restricted. CD8+ T cells are ___ restricted.

Answer 3

CD4+ T cells are class II MHC restricted. CD8+ T cells are class I MHC restricted.

Question 4

Antigen capture and DC migration

Answer 4

Question 5

Naive T cell activation

Answer 5

Question 6

Antigen processing takes place in. . .

Answer 6

the antigen-presenting cell (be it a professional APC or some random nucleated cell bearing a class I MHC)

Question 7

Class I and Class II MHC Structure

Answer 7

Question 8

Three types of Class I MHC

Answer 8

HLA-A

HLA-B

HLA-C

Question 9

Three types of Class II MHC

Answer 9

HLA-DP

HLA-DQ

HLA-DR

Question 10

Human HLA locus (in the genome)

Answer 10

Question 11

MHC genes, as a whole, are more ___ than any other genes in the genome.

Answer 11

MHC genes, as a whole, are more polymorphic than any other genes in the genome.

Question 12

If there are so many alleles, why are family members likely to be histocompatible?

Answer 12

Because all of the genes are at the same locus, they are usually inherited as a single HLA haplotype with Mendelian inheritance.

Question 13

Properties of MHC molecules

Answer 13

Question 14

How MHCs bind peptides

Answer 14

Question 15

Why have multiple types of a single class of MHC?

Answer 15

Because they bind peptides at different sites, thus enabeling binding of a greater number of peptides.

Question 16

How do class I and class II MHC not accidentally trigger a TCR meant for the other complex?

Answer 16

1. This is in part the role of the CD4 or CD8 coreceptor
2. The antigens are not in the same part of the binding cleft! Even ignoring CD4/CD8, this makes it practically impossible.

Question 17

MHC genes are expressed. . .

Answer 17

codominantly

Question 18

One individual has ___ types of MHC.

Answer 18

12!

3 class I and 3 class II from mom,

another 3 class I and 3 class II from dad.

Question 19

MHCs are often upregulated by. . .

Answer 19

RTKs or other growth or activity-related receptors

Question 20

Class II MHC loading pathway

Answer 20

Question 21

______ contains N‐terminal sorting signals that deliver the class II MHC to the specialized endosomal compartment where HLA‐DM and the antigen peptides are located.

Answer 21

The invariant chain contains N‐terminal sorting signals that deliver the class II MHC to the specialized endosomal compartment where HLA‐DM and the antigen peptides are located.

Question 22

Class I MHC loading pathway

Answer 22

Question 23

Immunoproteasome

Answer 23

Type of proteasome found in APCs. Chops up peptides to be the perfect length for Class I MHC binding.

Question 24

Transporter associated with antigen (TAP) pump

Answer 24

Pumps the peptides generated by the immunoproteasome into the lumen of the rough ER to be loaded onto maturing class I MHC molecules, which are conveniently held in place around the TAP pump by specialized chaperones.

Question 25

Major differences between Class I and Class II MHC processing

Answer 25

Question 26

Cross-presentation

Answer 26

Delivery of proteins from the phagosome or endosome into the cytosol, and then proteasomal processing of these proteins. This is a special property of DCs, and is vital for the activation of naive CD8⁺ T cells.

Question 27

Cross presentation loading pathway

Answer 27