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BMS 150 > Immunology 4 > Flashcards

Immunology 4 Flashcards

1
Q

T or F: antigens must be presented to a T-cell in order for them to recognize the antigen

A

True

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2
Q

what are HLA proteins?

A

human leukocyte antigen protein
present to the T-cell with antigens bound to it

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3
Q

what are the 2 types of HLA proteins

A

HLA class I
HLA class II

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4
Q

what do HLA class I proteins interact with?

A

cytotoxic T-cells and binds intracellular antigens - interact with a CD8 co-receptor on the cytotoxic T-cell

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5
Q

what do HLA class II proteins interact with?

A

T-helper cells and binds extracellular antigens - interacts with CD4 co-receptor on the T-helper cell

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6
Q

HLA type I molecule subtypes are all indicated by the designation…

A

A, B, or C

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7
Q

HLA type II molecule subtypes are all indicated by the designation…

A

D

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8
Q

HLA-1 proteins bind intracelular antigens via the ?

A

endogenous pathway

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9
Q

explain the endogenous pathway

A

antigenic peptide come from the cytosol, the peptide is derived from proteasomal degradation of foreign proteins, the peptide is then transported into the RER to be loaded onto the HLA-1 protein, then the loaded HLA-1 is then expressed on the cell surface

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10
Q

what are immunoproteosomes?

A

specialized proteasomes that are very good at presenting HLA-1 bound peptides to T-cells

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11
Q

what is the protein that translocate the peptide fragment into the RER for loading onto the HLA-1?

A

TAP

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12
Q

what are the receptors that increase transcription of HLA-1 protein in the presence of intracellular invaders?

A

NOD-like receptors

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13
Q

what does NOD-like receptors activate that in turn increase transcription of HLA-1 proteins

A

NFkB

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14
Q

what is the protein that inhibit NFkB and is phosphorylated and degraded when you need to increase the transcription of HLA-1 protein?

A

IkB (inhibitory protein)

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15
Q

T or F: cytokines can also increase the expression of HLA-1 molecules

A

true

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16
Q

what cytokines can increase the expression of HLA-1 molecules

A
  • both type 1 and type 2 interferons
  • tumour necrosis factor alpha (TNFa)
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17
Q

Once a peptide-bound HLA-1 is expressed on the surface of a cell, what happens next?

A
  • It can bind a CD8+ T-cells Cytotoxic T cell and activate it
  • Once activated, a cytotoxic T-cells can kill infected cells by inducing apoptosis
18
Q

HLA-2 types are expressed exclusively on ?

A

antigen presenting cells (APCs)

19
Q

what are the two types of antigen presenting cells categorized into?

A

“professional” and “non-professional”

20
Q

what are the “professional” APCs?

A
  • dendritic cells
  • macrophages
  • B-cells
21
Q

what are the “non-professional” APCs?

A
  • fibroblasts
  • glial cells
  • pancreatic beta cells
  • thymic epithelial cells
  • intraepithelial lymphocytes
  • vascular endothelial cells
22
Q

Dendritic cells constitutively (aka always) express ? and are very good at co-stimulating helper T cells

A

high levels of HLA-2

23
Q

Macrophages need to be ? before they express HLA-2, but they are also good at co-stimulating helper T-cells

A

activated

24
Q

B-cells constitutively express HLA-2 at ? and are good at co-stimulating helper T-cells

A

low levels

25
Q

Nonprofessional APCs will only express HLA-2 under

A

particular conditions

26
Q

HLA-2 proteins bind extracellular antigens via the ?

A

exogenous pathway

27
Q

HLA-2 expression is up-regulated by ? such as ?

A

particular cytokines
- interferon-gamma (IFN-y) (except for B-cells)
- IL-4

28
Q

what needs to be upregulated in concurrence with HLA-2 expression

A

phagocytosis

29
Q

What is the source of the peptides that are loaded onto the HLA-2

A

Phagocytosis

30
Q

Phagocytosis by B-cells can be ?

A

antibody-mediated

31
Q

Antigen binds to specific antibody on the surface of the B-cell (aka B-cell receptor) Antigen and the antibody are phagocytosed together, this process is called

A

receptor-mediated endocytosis

32
Q

How do we ensure an cytosolic antigen isn’t loaded onto an HLA-2 (rather than an HLA-1) in the RER?

A

In the RER, the HLA-2 protein associates with the invariant chain, This prevents a cytosolic antigen from being loaded onto the HLA-2 while in the RER

33
Q

As the HLA-2 containing vesicle merges with the phagosome/endosome containing the antigen, the ? is chopped up. The “chopped version” is called ? , and it will remain bound to the HLA-2 peptide binding region until displaced

A

invariant chain
CLIP

34
Q

Once a peptide-bound HLA-2 is expressed on the surface of a cell, what happens next?

A

It can bind a CD4+ T-cells, ie, a helper T-cell, and activate it

35
Q

Helper T-cells need a co-receptor to bind to the HLA-2 molecule, this co-receptor is known as ?

A

CD4

36
Q

Helper T-cells also need a co-stimulatory activation, a key co-stimulatory interaction is ?

A

CD28 (on T-cell) with CD80/86 on the APC

37
Q

only what have the capacity to express CD80/86 (CD28 ligand)

A

professional APCs

38
Q

How does CD28 signaling add to the effects of TCR signaling

A
  1. Enhances the strength of signal between the T-cell and the antigen presenting cell
  2. Initiates a cell-signaling cascade to promote T cell survival and proliferation
    ○ CD28 will recruit PI3 Kinase
39
Q

The interactions between the T-cell and the antigen presenting cell can be divided into 2 categories:

A

CSMAC and PSMAC

40
Q

what is CSMAC

A

central supremolecular activation complex
- TCR and HLA-2 (with co-activator CD4)
- Co-stimulator interaction (CD28 and CD80 /86)

41
Q

what is PSMAC

A

peripheral supramolecular activation complex
- Includes other receptor-ligand interactions that help to strength the connection between the T-cell and APC to sustain the signal

BMS 150 (15 decks)

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