L13 MHC

Question 1

what cells do not have MHC

Answer 1

red blood cells

Question 2

where is MHC I expressed

Answer 2

all nucleated cells

Question 3

where is MHC II expressed

Answer 3

antigen presenting cells; DC, B cells, monocytes and macrophages

Question 4

structure of MHC I

Answer 4

single chain covalently bound to soluble molecule beta II mycoglobulin

Question 5

what is mycoglobulin for ?

Answer 5

stabilise the single chain MHC I

Question 6

how long is MHC I

Answer 6

9 amino acids

Question 7

structure of MHC II

Answer 7

2 chains: alpha and beta

Question 8

which is the variable chain in MHC II

Answer 8

beta chain

Question 9

how long are the amino acid chains in MHC

Answer 9

> 15

Question 10

Where do MHC I get their peptides

Answer 10

cytoplasmic antigen

Question 11

where does MHC II get peptides

Answer 11

outside the cell brought in by phagocytosis etc
content is digested by phagolysome and peptides are realeased
MHC II and peptide is loaded onto cell surfaceq

Question 12

what happens when an infected cell dies

Answer 12

DC take it up and destroys content

Question 13

what is the process of cross priming

Answer 13

when antigen leaks out of a lysosome and into the cytoplasm

it is then loaded onto MHC I and activates the cytotoxic CD8 T cell

Question 14

what prevents peptides longer than 9-10 amino acids from binding

Answer 14

conserved amino acids

Question 15

what does MHC require ot be stable

Answer 15

peptide bound to the anitgen binding groove

Question 16

what happens to MHC that is non-peptide bound

Answer 16

recycled from cell surface or doesnt reach surface

Question 17

if we are not chronically infected why do we express MHCI and II

Answer 17

in absence of infection almost 100% of MHC will be loaded with self-peptides

Question 18

what stabilises immature MHC II and prevents premature loading of self-peptide

Answer 18

Li chaperone/protein

Question 19

when and how is Li cleaved

Answer 19

just prior to peptide loading by proteases

Question 20

what do antigen presenting cells express

Answer 20

MHC I

MHC II

Question 21

what type of MHC is only on antigen presenting cells

Answer 21

MHC II

Question 21

what type of MHC is only on antigen presenting cells

Answer 21

MHC II

Question 22

where do most polymorphism of MHC occur

Answer 22

Beta chain of MHC II

Question 23

hoe are peptide bound to the MHC groove

Answer 23

anchor residues

Question 24

what is the primary role of the invariant chain

Answer 24

stabilise MHC II