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Immunology Med School wk 1 > Adaptive Immunity activation > Flashcards

Adaptive Immunity activation Flashcards

1
Q

Class I MHC

who expresses, what do they present

A

all nucleated cells (obviously not RBCs)
they present peptides 8-11 amino acids in length
“present endogenously processed peptides”

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2
Q

How many genes do humans have for the MHC 1 complex?

A

3, coding for 6 alleles (one from each parents)

HLA-A
HLA-B
HLA-C

highly polymorphic and co-dominantly expressed

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3
Q

What is significant about polymorphic proteins?

A

they have the same shape but they differ by one or a few amino acids

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4
Q

how many allotypes of HLA-A and HLA-B are there?

A

200- A

400- B

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5
Q

what about the beta-2 protein?

A

it is not polymorphic.

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6
Q

what recognizes MHC class I?

A

CD8 cytotoxic lymphocytes

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7
Q

what does it mean to say CD*+ T cells express endogenous peptides?

A

these are intracellular pathogens like viruses that infect the host cell

“surface protein fragments manufactured by the cells”

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8
Q

MHC I hold peptides of what length?

A

8-9 a.a. long

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9
Q

what kind of bonds are at work between the peptide and the MHC and TCR?

A

non-covalent interactions

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10
Q

what components of the MHC holds to the peptide?

A

alpha1 and alpha2

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11
Q

CD8 does what

A

stabilizes interaction between TCR and MHC

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12
Q

the CDR is on the _______

A

TCR

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13
Q

is the CDR on the MHC or the TCR

A

TCR

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14
Q

where are HLA-gene coded regions on the MHC?

A

the alpha1 and alpha2 peptide binding region

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15
Q

where does CD8 bind on the MHC 1 molecule?

A

on the alpha3 region

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16
Q

what’s the order of the CDR regions from the lateral edges of the CDR regions to the most medial

A

CDR2-CDR1-CDR3

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17
Q

in the interior of the cell, what are MHC I’s doing?

A

sampling all the proteins

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18
Q

what are CTLs doing?

A

always sampling the MHC I of all the cells it contacts

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19
Q

Ag processing for class I MHC

how does it happen, what significant proteins are involved

A

old proteins are destroyed by the proteosome and chopped into pieces IN THE CYTOPLASM

transport proteins tap 1 and 2 carry all the garbage peptides out into the endoplasmic reticulum

these peptides become loaded into the grooves of class I MHC

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20
Q

Class II MHC: polymorphic or not

A

HIGHLY polymorphic

21
Q

What size peptides do MHC II hold?

A

13-25 a.a.

22
Q

Structure of MHC II

A

two non-covalently bonded peptide chains (alpha 1 and beta 1) both are highly polymorphic.

23
Q

what parts of the MHC do the peptides interact with?

A

both the alpha 1 and beta 1 chains which have CDR

24
Q

the regions where the CD4 interacts with the MHC II is called

A

conservative

25
Q

MHC I was loaded in the endoplasmic reticulum, where are MHC II’s loaded?

A

in endosomes

26
Q

the invariant chain: GO!

A

MHC II is synthesized in the endoplasmic reticulum; before it leaves, it’s loaded with an “invariant” chain to prevent it from grabbing any self-peptides as it travels around the cell.

inside the transport vesicle the invariant chain is cleaved to the “clip fragment”

27
Q

clip

A

what remains of the invariant chain after it’s been degraded in the endosome, it’s the surrogate peptide in the MHC II until HLA-DM facilitates the release

28
Q

HLA-DM

A

facilitates clips release from MHC II so peptides can be loaded

29
Q

From where do the peptides that MHC II loads come from?

A

from phagocytized/endocytized/pinocytized

30
Q

CD8 binds to the ____ domain of the MHC I molecule

A

alpha3

31
Q

CD4 binds to the ___ domain of the MHC II molecule

A

beta2

32
Q

broadly speaking, what distinguishes MHC I and II from one another apart from the big things?

A

MHC I seems to display intracellular pathogens and MHC II displays danger signals from outside the cell

there is the exception of cross presentation

33
Q

the exogenous presentation of peptides via the MHC class 1 pathway is achieved how?

A

cross presentation

34
Q

explain cross presentation

A

this is when peptides usually presented by MHC I are picked up exogenously: say a virus infected cell dies, and the cellular detritus is picked up by a professional APC….

because it’s exogenous, we expect MHC II
because these are viral materials, we also expect MHC I

the cell solves this by leaking the peptides into the cytoplasm, thus they will be treated by MHC I in an MHC II carrying cell

35
Q

the “short version” of cross presentation

A

when professional APCs present exogenous material via the MHC I pathway.

the debris was “leaked” into the cytoplasm and thus processed via the proteosome.

36
Q

Ags recognized by B cells can be in what forms

A

soluble are cell surface associated form

37
Q

effector B cells are found where

A

lymphoid organs

38
Q

What are the two B cell surface BCRs?

A

IgM and IgD

39
Q

What are the components of the BCR complex?

A

the BCR and two other peptides: Igbeta/Igalpha

40
Q

What are Igalpha/Igbeta?

A

they are associated disulfide linked heterodimers which, when BCRs bind an epitope, initiated an intracellular signaling cascade that leads to B cell activation

41
Q

TCR’s are composed of

A

alpha and beta chains

42
Q

what makes the TCR chains what they are

A

they both have constant and variable regions

43
Q

TCRs are associated with what molecules?

A

3 invatiant domains

epsilon-delta —– gamma-epsilon and two zeta chains underneath the TCR complex

44
Q

CD3

A

identification marker for TCR

epsilon delta and gamma epsilon

45
Q

What do APCs need besides the MHC to stimulate T cells?

A

co-stimulators

46
Q

resting-APC

A

MHC expression w/out co-receptor expression

47
Q

activated-APC

A

MHC expression + co-receptor

48
Q

Non-traditional gamma-delta T cells

where are they a major population, what’s interesting about their CD expressions, their significance

A 
They don't express CD4/CD8
reside largely in epithelia tissues 
recognition of lipid antigens 
have no memory cells 
TCR repertoire is limited

Immunology Med School wk 1 (36 decks)

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