Hudig: MHC

Question 1

This disease is often associated with the HLA B27 locus

Answer 1

ankylosing spondylitis

**this is an MHC1 locus

Question 2

What are the two components of an MHC Class I protein?

Answer 2

MHC class I alpha + beta2microglobulin

Question 3

What are two components of an MHC Class II protein?

Answer 3

MHC class II alpha + beta protein chain

Question 4

This is a large multigene complex on one chromosome

Answer 4

human major histocompatibility complex

Question 5

MHC class I is (blank) and also (blank)

Answer 5

multigenic; multiallelic

Question 6

How many HLA class I loci are there? What are they called?

Answer 6

3; HLA-A, HLA-B, HLA-C

Question 7

How many different HLA-B heterozygous pairs are possible in a human?

Answer 7

+1,000,000

Question 8

many alleles for a single locus in a population

Answer 8

multiallelic

Question 9

many alleles frequently used in the population

Answer 9

polymorphic

Question 10

more than one locus for the family of proteins (e.g., HLA class I A, B and C are different genes)

Answer 10

multigenic

Question 11

The MHC I is multiallelic, multigenic, and expressed (blank).

Answer 11

co-dominantly

Question 12

How many different MHC I proteins will there be on a single cell of a completely heterozygous person?

Answer 12

6

*There are 3 loci with 2 alleles at each (one from ma, one from dad) - both are expressed on the cell surface due to co-dominance

Question 13

Where in the body would you find a cell with MHC I molecules?

Answer 13

In all cells except RBCs

Question 14

Describe the structure of the MHC I proteins

Answer 14

1 alpha chain (comprised of three parts) attached to 1 Beta2-microglobulin

Question 15

Which portion of the MHC I protein forms a peptide-binding cleft?

Answer 15

the alpha chain

**this cleft can hold peptides of 9-11AA

Question 16

What is unique about each MHC allelic protein?

Answer 16

each MHC allelic protein will hold slightly different peptides

**furthermore, each MHC allele can bind thousands of different peptides

Question 17

Why is MHC I allelic variation important?

Answer 17

It maximizes the ability of MHC molecules to present a DIVERSE array of antigenic peptides

**side note: most people inherit MHC I alleles that are able to bind some influenza peptides; if not… SOL

Question 18

What is meant by MHC antigen restriction?

Answer 18

A memory CTL must match both the antigen (peptide) and the MHC I protein in order to kill.

**this makes it challenging to test CTL anti-viral vaccines, because you can only use them with target cells that have the same MHC I as the immune donor of the CTLs

Question 19

MHC Class II proteins are always present on (blank) and are inducible in (blank) during inflammation

Answer 19

APCs (macrophages, dendritic cells); endothelial cells

Question 20

Describe the structure of the MHC II protein.

Answer 20

1 beta chain, 1 alpha chain; open-ended so it can hold large peptides of 20-30AA

Question 21

MHC Class II is also (blank) and (blank), much like MHC Class I

Answer 21

multigenic; multiallelic

Question 22

How many HLA class II loci are there? What are they called?

Answer 22

3; DP, DQ, DR

Question 23

What cells lack both MHC I and II?

Answer 23

RBCs

Question 24

What cells have only MHC I?

Answer 24

neutrophils
hepatocytes
kidney cells
brain cells

(cells that are not antigen presenting cells)

Question 25

What kind of cells have MHCII?

Answer 25

``` cells in lymphoid tissues T cells B cells macrophages APCs ```

Question 26

Do cells with MHC II also have MHC I?

Answer 26

Yes **all cells have MHC1 except RBCs

Question 27

List some diseases associated with certain HLA alleles

Answer 27

ankylosing spondylitis Type I diabetes systemic Lupus Eryhtematosis

Question 28

Why are MHC I and II barriers to organ transplantation?

Answer 28

T cells have a high frequency of recognition of foreign MHC molecules!!

Question 29

Tissue grafted within one person or between genetically identical mice or twins Usu 100% successful

Answer 29

autograft

Question 30

tissue grafted between HLA (& other loci) allogeneic individuals Usu rejected within 2 weeks if no immunosuppression

Answer 30

allograft

Question 31

When do you have the best chance of survival after an allograft?

Answer 31

when MHC haplotypes are matched

Question 32

T/F: Even when you have complete HLA matching, there are other genetic differences that may cause graft rejection.

Answer 32

True

Question 33

T/F: There is an MHC Class III that we are not too concerned with, because these genes are mostly nonallelic.

Answer 33

True

Question 34

Linked sets of genes usually inherited as one unit, one is inherited from each parent

Answer 34

haplotypes

Question 35

How many MHC haplotypes does each person have?

Answer 35

2 | *one from ma, one from dad

Question 36

How is the MHC haplotype usually inherited?

Answer 36

as one single unit, as if it were only one gene

Question 37

What are superantigens?

Answer 37

they are antigens made by several bacteria, including Staph, that bind to a very large number of T cells and trigger MASSIVE T cell responses **they sort of bypass normal MHC-peptide presentation and activate T cells instantly

Question 38

Superantigens bind to 2 sites simultaneously. What are they?

Answer 38

1. regions of MHC II chains | 2. T cell receptor V betas

Question 39

Superantigens bypass normal (blank) and often cause disease

Answer 39

MHC II antigen presentation *no need to process the peptide and present it as a foreign body

Question 40

Bypass normal antigen-presentation and trigger T cells rapidly, including cytokine release. Cytokine release causes diseases like toxic shock syndrome and staph. food poisoning

Answer 40

superantigens

Question 41

What are two conditions that can be caused by superantigens?

Answer 41

rapid food poisoning by staphylococci enterotoxin | toxic shock syndrome

Question 42

Which subclass of TCRs can superantigens bind t?

Answer 42

Vbetas (minigenes) contained on T cell receptors