L13 MHC Flashcards Preview

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Flashcards in L13 MHC Deck (25)
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1
Q

what cells do not have MHC

A

red blood cells

2
Q

where is MHC I expressed

A

all nucleated cells

3
Q

where is MHC II expressed

A

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

4
Q

structure of MHC I

A

single chain covalently bound to soluble molecule beta II mycoglobulin

5
Q

what is mycoglobulin for ?

A

stabilise the single chain MHC I

6
Q

how long is MHC I

A

9 amino acids

7
Q

structure of MHC II

A

2 chains: alpha and beta

8
Q

which is the variable chain in MHC II

A

beta chain

9
Q

how long are the amino acid chains in MHC

A

> 15

10
Q

Where do MHC I get their peptides

A

cytoplasmic antigen

11
Q

where does MHC II get peptides

A

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

12
Q

what happens when an infected cell dies

A

DC take it up and destroys content

13
Q

what is the process of cross priming

A

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

14
Q

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

A

conserved amino acids

15
Q

what does MHC require ot be stable

A

peptide bound to the anitgen binding groove

16
Q

what happens to MHC that is non-peptide bound

A

recycled from cell surface or doesnt reach surface

17
Q

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

A

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

18
Q

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

A

Li chaperone/protein

19
Q

when and how is Li cleaved

A

just prior to peptide loading by proteases

20
Q

what do antigen presenting cells express

A

MHC I

MHC II

21
Q

what type of MHC is only on antigen presenting cells

A

MHC II

21
Q

what type of MHC is only on antigen presenting cells

A

MHC II

22
Q

where do most polymorphism of MHC occur

A

Beta chain of MHC II

23
Q

hoe are peptide bound to the MHC groove

A

anchor residues

24
Q

what is the primary role of the invariant chain

A

stabilise MHC II