9 - MHC

Question 1

When do T and B cells undergo random recombination?

Answer 1

when they undergo maturation

Question 2

What do BCRs recognize and bind to?

Answer 2

free (soluble) antigen part of a larger pathogen or toxin

Question 3

What are the 2 necessary things that TCRs must recognize and bind to?

Answer 3

antigenic (antigen-derived) peptides | MHC molecule that is bound to the antigenic peptide

Question 4

What does exogenous mean?

Answer 4

extracellular

Question 5

What does endogenous mean?

Answer 5

intracellular

Question 6

What are the 3 functions of MHC molecules?

Answer 6

antigen-presenting molecules | form stable complexes with peptide ligands | display antigen on cellular surface for TCR engagement

Question 7

Which cells express MHC I?

Answer 7

all nucleated cells

Question 8

Which cells express MHC II?

Answer 8

APCs or cells involved in immune responses

Question 9

What family are MHC I and II both part of?

Answer 9

Ig (immunoglobulin) superfamily | sticky domain

Question 10

How long can the peptide be to fit into MHC I?

Answer 10

8-10 amino acids

Question 11

What 2 polypeptides that make up the MHC I structure?

Answer 11

large transmembrane alpha chain | small beta-2 microglobulin protein for stability

Question 12

Which polypeptide makes up the peptide binding groove of the MHC I?

Answer 12

alpha chain

Question 13

What polypeptides make up the MHC II structure?

Answer 13

heterodimeric transmembrane alpha and beta chains

Question 14

How long can the peptide be to fit into MHC II?

Answer 14

13-18 amino acids

Question 15

Which T-cells do MHC I molecules present peptides to?

Answer 15

CD8 CTLs

Question 16

Where are the peptides that bind to MHC I derived from?

Answer 16

endogenous intracellular proteins

Question 17

Which T-cells do MHC II molecules present peptides to?

Answer 17

CD4 Th cells

Question 18

Where are the peptides that bind to MHC II derived from?

Answer 18

exogenous extracellular processed antigens

Question 19

If there are no foreign peptides for MHC I to present, what does MHC I do and why?

Answer 19

will present self-proteins on its surface | this is a way the immune system checks if cells are self and are healthy (not cancerous)

Question 20

What is the organelle that protein (self or foreign) will be randomly broken down in?

Answer 20

proteosome

Question 21

What will MHC I do if the cell is infected with an intracellular bacteria or virus or is a tumor cell?

Answer 21

MHC I will load viral, bacterial, or cancer-related protein on its peptide-binding groove and present it on surface | CTLs will be activated if it recognizes the peptide

Question 22

What are the 3 types of APCs?

Answer 22

B-cells | macrophages | dendritic cells

Question 23

What is the role of MHC II?

Answer 23

helps direct responses against things that shouldn’t be in our system &raquo_space;> display those peptides to activate Th cells

Question 24

What are the 4 things that can induce change in MHC expression?

Answer 24

genetic regulatory components | viral interference | cytokine-mediated signaling | steroids

Question 25

How do genetic regulatory components influence MHC expression to change?

Answer 25

PRR signaling can lead to more expression of MHC molecules | promoters can drive transcription during times of infection due to PRRs

Question 26

How does viral interference influence MHC expression to change?

Answer 26

viruses shut down MHC I expression because it targets the cells they are in for destruction via NK cell

Question 27

How does cytokine-mediated signaling influence MHC expression to change?

Answer 27

some cytokines such as TNF and Type-I IFN can upregulate MHC expression

Question 28

How do steroids influence MHC expression to change?

Answer 28

can upregulate it | steroids cause inflammation

Question 29

MHC alleles are ____ expressed.

Answer 29

co-dominantly

Question 30

What is an issue that MHC prompts and why?

Answer 30

presents issues for transplantation because MHC must be compatible

Question 31

In terms of MHC compatibility, who can Person A donate tissue to or from? (4)

Answer 31

sibling | to offspring | from parent | with self

Question 32

In terms of MHC compatibility, who can NOT Person A donate tissue to or from? (3)

Answer 32

to parent | from offspring | with partner

Question 33

What will happen if the donated tissue does not match the recipient's MHC?

Answer 33

recipient's immune system will attack and reject donated tissue

Question 34

What is MHC restriction?

Answer 34

MHC compatibility