Antigen Capture and Presentation Flashcards

1
Q

where are antigens transported from and to

A

transported from tissue/mucosa to lymphoid organs

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2
Q

when antigens are transported to the lymphoid organs, what occurs

A

recognition by T cells

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3
Q

what resides in tissues and captures microbes and antigens

A

dendritic cells

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4
Q

how are cell-free antigens drained

A

via lymphatic vessels or enter blood stream

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5
Q

which type of DC are the majority

A

classical DC

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6
Q

where do classical DC (cDC) reside in the lymph node

A

T cell zone

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7
Q

what do immature DC do

A

capture and process antigen

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8
Q

how are DC activated

A

PRR

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9
Q

where do DC migrate to after they’re activated and how do they migrate

A

LN via chemokine gradient

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10
Q

what is upregulated during DC migration

A

chemokine receptors (CCR7) and costimulatory molecules

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11
Q

what do mature DC do

A

present protein antigens to T cells

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12
Q

what do T cells recognize on APCs

A

they recognize peptide antigens displayed by MHC molecules on the APC

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13
Q

where is the peptide located within the MHC

A

the pocket

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14
Q

what are the Human MHC proteins called

A

human leukocyte antigens (HLA)

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15
Q

T/F the genes are not polymophic

A

F. they are highly polymorphic

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16
Q

what are the two susceptibility factors for periodontitis

A

HLA-A9 and HLA-B15

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17
Q

T/F in both MHC I and MHC II the peptide binding cleft is located at the amino terminal

A

True

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18
Q

describe the chains of MHC I

A

one alpha chain, composed of a1, a2, and a3

19
Q

what is variable and invariable in MHC I

A

a1 and a2 are variable, a3 is invariant

20
Q

how many AA are in a MHC I

A

8-9 AA peptide

21
Q

what is the a chain associated with in MHC I

A

beta2-microglobulin

22
Q

describe the chains of MHC II

A

one alpha chain, composed of a1 and a2 and one beta chain composed of B1 and B2.

23
Q

the groove accommodates how many AAs in MHC II

A

10-30 AA peptide

24
Q

where is the variability in the MHC II

A

variability in a1 and B1, invariable in a2 and B2

25
Q

CD8 T cells only recognize peptide presented by which MHC

A

MHC class 1

26
Q

what binds to CD8 T cells

A

a3 (invariant portion of alpha chain) binds CD8 on CD8 T cell

27
Q

where do peptides bind in the cleft

A

floor of the cleft

28
Q

where does TCR bind in the cleft

A

side and top of cleft

29
Q

CD4 T cells only recognize peptides presented by which MHC

A

MCH II

30
Q

what binds to CD4 on CD4 T cells

A

B2 (invariant portion of beta chain) on MCH II

31
Q

what does MHC polymorphism ensure

A

that a population can deal with microbe diversity

32
Q

how many different kinds of MHC class I

A

6

33
Q

how many different kinds of MHC class II

A

6-8

34
Q

what is MHC II expressed on and what is it induced by

A

expressed on APC and induced by IFNy

35
Q

what is MHC I expressed on

A

all nucleated cells (all cells but RBCs)

36
Q

T/F one APC cannot display multiple peptides

A

F. One APC can display multiple peptides

37
Q

what does loading of peptides do during MHC assembly

A

stabilized expression of MHC on cell surface

38
Q

how long can binding last

A

up to days to maximize interaction with T cells

39
Q

how are extracellular proteins (tumor, bacteria) processed

A

processed in endosome/lysosome and peptides displayed on MHC class II to CD4 cells

40
Q

what are the three steps of processing extracellular proteins

A
  1. antigen INTERNALIZATION
  2. antigen DEGRADATION in lysosome
  3. antigen (peptide) ASSOCIATION with class II molecules in endosome
41
Q

how are cytosolic proteins processed

A

viruses & bacteria that escape phagosome are processed by proteasome and ER and peptides displayed on MHC class 1 to CD8 cells

42
Q

what are the 3 steps of processing cytosolic proteins

A
  1. antigen DEGRADATION by proteasome
  2. peptide TRANSPORT via TAP in ER
  3. antigen (peptide) ASSOCIATION with class I molecules
43
Q

MHC II presents antigens to:

A

helper T cells

44
Q

MHC I presents antigens to:

A

cytotoxic T lymphocytes