MHC Flashcards

1
Q

What do antigen receptors of B cells recognize?

A
  • macromolecules
    • proteins
    • polysaccharides
    • lipids
    • nucleic acids
  • small chemicals in soluble form
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2
Q

what do antigen receptors of T cells recognize

A
  • peptide fragments of protein antigens

- only when present on MHC cells

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3
Q

T-cell mediated immune responses only against

A
  • protein antigens
  • produced in host cells
  • taken up by host cell
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4
Q

antigens can only be recognized in the proper context

A
  • location (anatomic)

- setting (micranatomic/molecular)

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5
Q

where does antigen presentation occur

A
  • lymph node collects antigen from epithelium and connective tissues
  • blood-borne antigens are captured by antigen-presenting cells in the spleen
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6
Q

langerhans cells

A
  • dendritic cells in the skin

- as they capture antigen, they get signals to travel to T cell areas within lymph nodes

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7
Q

where are proteins displayed or recognition by T lymphocytes

A
  • peripheral lymphoid organs
  • lymph nodes
  • spleen
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8
Q

major location of conventional dendritic cells

A
  • tissues
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9
Q

major location of plasmacytoid dendritic cells

A
  • blood

- tissues

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10
Q

major cytokines produced by conventional dendritic cells

A
  • pro-inflammatory
  • TNF
  • IL-6
  • IL-12
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11
Q

major cytokines produced by plasmacytoid dendritic cels

A
  • type I interferons
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12
Q

major functions of conventional dendritic cells

A
  • induction of T cell responses against most antigens
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13
Q

major functions of plasmacytoid dendritic cells

A
  • antiviral innate immunity

- induction of T cell responses against viruses

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14
Q

after dendritic cells capture microbial antigens

A
  • activated
  • and leave their location
  • migrate to draining lymph nodes
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15
Q

what attracts dendritic cells to the lymph nodes

A
  • chemokines produced in the lymphatics and nodes
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16
Q

how to the dendritic cells mature and acquire the ability to present antigen

A
  • in response to signals induced by the microbe such as Toll like receptor signals and cytokines
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17
Q

immature dendritic cells express

A
  • surface receptors that capture microbial antigen
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18
Q

mature dendritic cells express

A
  • high levels of MHC molecules and costimulators

- to stimulate T cells

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19
Q

dendritic cell class II MHC - constitutive or inducible

A
  • constitutive
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20
Q

dendritic cell class II MHC increases with

A
  • maturation
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21
Q

dendritic cell class II MHC increases by (cytokine)

A
  • interferon gamma
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22
Q

dendritic cells costimulators - constitutive or inducible

A
  • constitutive
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23
Q

dendritic cells costimulators increases with

A
  • maturation
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24
Q

dendritic cells costimulators inducible by

A
  • TLR ligands
  • interferon gamma
  • CD40-CD40L interactions
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25
Q

dendritic cells principle function

A
  • initiation of T cell responses to protein antigens
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26
Q

macrophages class II MHC - constitute or inducible

A
  • inducible by interferon gamma

INTERFERON GAMMA MAKES MACROPHAGES HUGE AF

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27
Q

macrophages costimulators - constitutive or inducible

A
  • inducible by:
  • TLR ligands
  • interferon gamma
  • CD40-CD40L interactions
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28
Q

macrophages principal function

A
  • effector phase of cell-mediated immune responses
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29
Q

B lymphocytes class II MHC - constitutive or inducible

A
  • constitutive
30
Q

B lymphocytes class II MHC increased by

A
  • IL-4
31
Q

B lymphocytes costimulators induced by

A
  • CD40-CD40L interactions

- antigen receptor cross linking

32
Q

B lymphocytes function

A
  • antigen presentation to CD4+ helper T cells in humoral immune responses
33
Q

MHC I pathway (intrinsic or extrinsic)

A
  • intrinsic
34
Q

MHC II pathway (intrinsic or extrinsic)

A
  • extrinsic
35
Q

3 processing pathway

A
  • intracellular
  • intrinsic
  • extrinsic
36
Q

3 presentation pathways

A
  • extracellular/surface
  • multi-molecular
  • multi-cellular
37
Q

MHC gene products in humans are called

A
  • human leukocyte antigens

- HLAs

38
Q

most important HLAs

A
  • Class I and Class II
39
Q

HLA gene and haplotypes

A
  • certain haplotypes can determine if you are protected or predisposed to certain autoimmune diseases
40
Q

MHC gene expression

A
  • codominantly expressed
41
Q

MHC genes and diversity

A
  • highly polymorphic
42
Q

co-dominant expression

A
  • both parental alleles of each MCH gene are expressed
43
Q

significance of codominant expression for MHC

A
  • increases the number of different MHC molecules that can present peptides to T cells
44
Q

significant of polymorphous genes for MHC

A
  • ensures that different individuals are able to present and respond to different microbial peptides
45
Q

Class II MHC found on

A
  • dendritic cells
  • macrophages
  • B cells
46
Q

Class I MHC found on

A
  • all nucleated cells
47
Q

MHC Class I chains

A
  • alpha chain

- beta-2 microglobulin (not coded in MHC)

48
Q

MHC Class I binding cleft

A
  • alpha 1 and alpha 2 domains
49
Q

size of peptide MHC Class I can bind

A
  • 8-11 AA in size
50
Q

part of Class I MHC that binds CD8

A
  • alpha 3
51
Q

polymorphisms in MHC Class I

A
  • mostly alpha 1 and 2
52
Q

MHC II chains

A
  • alpha and beta chains
53
Q

size of peptide MHC II can bind

A
  • 10-30 AA
54
Q

part of MHC II that binds CD4

A
  • beta 2
55
Q

number of antigens MHC can present at a time

A
  • only one peptide at a time

- peptides only

56
Q

how many MHC molecules on the surface

A
  • 10^5
57
Q

how what percentage of MHC must be bound to be activated

A
  • less than 1%
58
Q

significance of slow off rate of MHC molecule

A
  • displays bound peptide for long enough to be located by a T cell
59
Q

CD4 T cell responses

A
  • classic T helper
  • cell mediated immunity
  • humoral responses
  • T regulatory cells
60
Q

CD8 cell responses

A
  • classically CTL responses
  • kills infected cells
  • antiviral immunity
61
Q

MHC II enzymes responsible for peptide generation

A
  • endosomal and lysosomal proteases
62
Q

MHC I enzymes responsible for peptide generation

A
  • cytoplasmic proteasome
63
Q

site of peptide loading MHC II

A
  • specialized vesicles
64
Q

site of peptide loading MHC I

A
  • endoplasmic reticulum
65
Q

molecules in volved in transport of peptides and loading of MHC molecules on MHC II

A
  • invariant chain

- DM

66
Q

molecules in volved in transport of peptides and loading of MHC molecules on MHC I

A
  • TAP
67
Q

MHC II Pathway

A
  • uptake of EXTRACELLULAR proteins into vesicular compartments of APC
  • processing of internalized proteins in endosomal/lysosomal vesicles
  • biosynthesis and transport of class II MHC molecules to endosomes
  • association of processes peptides with class II MHC molecules in vesicles
  • DM provides the switch
  • expression of peptide MHC complexes on cell surface
68
Q

MHC Class I pathway

A
  • production of proteins in cytosol or phagosome bringing in
  • proteolytic degradation of proteins by proteasome
  • transport of peptides into ER by TAP for assembly
  • packaged in Golgi
  • released in exocytic vesicle for surface expression
69
Q

dendritic cells can also present to

A
  • CD8 T cells

- through MHC1 expression

70
Q

how dendritic cells present to CD8 T cells

A
  • infected cells and viral antigens picked up by APC

- cross-presentation of viral antigen

71
Q

roles of APC

A
  • co-stimulators
  • secrete cytokines
  • present a context for immune regulation
  • may limit immune responses
72
Q

important chromosome for human HLA

A
  • chromosome 6