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Immunology > Antigen Processing, Presentation, Co-stimulation > Flashcards

Antigen Processing, Presentation, Co-stimulation Flashcards

1
Q

In general, once an antigen presenting cell (APC) contacts an antigen (Ag) at the site of infection it will move into the ______

A

lymph circulation/ lymph node

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2
Q

CD8+ T cells are _______ restricted and recognize cytosolic proteins

A

MHC I

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3
Q

CD4+ T cells are _____ restricted and recognize extracellular and intravesicular pathogens

A

MHC II

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4
Q

What are naive B and T cells

A

inactivated B and T cells floating in the circulation

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5
Q

when would naive B and T cells move from the circulation into a lymph node ?

A

when a APC engulfs an antigen and transports it to the lymph node

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6
Q

What does it mean when saying antigen presentation is context dependant

A

Different immune responses under different conditions

Example : MHC I or MHC II

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7
Q

Antigen presentation acts as a bridge b/w Ag recognition and what ?

A

the full blown immune response

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8
Q

Is Ag recognition part of the innate or adaptive immune response

A

adaptive immune response

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9
Q

Successful Ag presentation results in ?

A

Activation of naive B and T cells

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10
Q

What are the 3 “professional” APC

A
  • Dendritic cells (Best)
  • Macrophages
  • B cells (rare)
  • These are majority, but more exist*
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11
Q

What can ALL nucleated cells do with regards to Ag presentation ?

A

Present endogenous Ag tagged with MHC I

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12
Q

Degradation/break down of cytoplasmic proteins occurs within ?

A

proteasome

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13
Q

Degradation/break down of endocytic proteins occurs within ?

A

lysosome

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14
Q

There are 2 main pathways in Ag presentation. One processes exogenous Ag with aid of _______ molecule, and the other processes endogenous Ag tagged w/________

A 
MHC II (CD4)
MHC I (CD8)
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15
Q

What are the names of the 2 pathways of Ag presentation, and what type of Ag do the recognize ?

A

Cytosolic Pathway - Endogenous Ag

Endocytic Pathway - Exogenous Ag

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16
Q

Explain the Cytosolic pathway of Ag presentation starting from the labeling of proteins via ubiquitin.

A

1 - Ubiquitin tags proteins(Ag) for degradation
2 - degradation (of Ag) occurs in proteasome
3 - TAP transports digested Ag peptides to lumen RER
4 - MHC I binds to Ag peptides
5 - Ag-MHC I complex transport to surface for interaction w/lyphmocytes

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17
Q

What are TAP’s

A

proteins that transport digested fragments of Ag protein into lumen of RER

18
Q

MHC I and MHC II are both synthesized where ?

A

RER

19
Q

What is the diff. b/w HLA-DM and HLA-DO

A

HLA-DM loads Ag in endocytic pathway

HLA-DO inhibits the loading of Ag (by blocking HLA-DM)

20
Q

clatherin coated pits are used to engulf/vesiclize Ag in what Ag presentation pathway

A

Endocytic Pathway (Exogenous Ag)

21
Q

Explain the Endocytic pathway of Ag presentation starting w/ Ag binding to cell surface

A

1 - Ag binds and internalized via endosomes
2 - digested in lysomes in Ag peptides
3 - HLA-DM triggers loading of Ag to MHC II

22
Q

what is the role of the invariant chain in the endocytic pathway

A

When bound to MHC II, it keeps MHC II from binding endogenous Ag

23
Q

what triggers the exchange from CLIP (Class II associated invariant chain peptide) to an Ag on the MHC II molecule

A

HLA-DM (loads the Ag)

24
Q

what is a haplotype

A

clusters of alternative forms of the same gene closely linked on the same chromosome

25
Q

What 3 things does the MHC haplotype influence

A
  • how individual responds to pathogens
  • susceptibility to disease
  • transplant success
26
Q

The MHC genes are highly polymorphic, what does this mean ?

A

10^13 different allele combinations (broad response) E

-reason why we can recognize so many different specific types of Ag’s

27
Q

A self MHC + a foreign Ag will elicit ___________ whereas a self MHC + self Ag will elicit ______

A

T cell response

NO T cell response

28
Q

All nucleated cells in the body can alert either CD4 or CD8 T cells, which is it ?

A

CD8 T cells via MHC I

29
Q

What results in a positive selection in MHC restriction and what results in a negative selection

A

Ag + MHC = positive selection

self + MHC = negative selection

30
Q

In order to get activation of a T cell, there are 2 signals needed in the immunological synapse, what are they ?

A

1 - MHC-Ag complex binds to TCR (T cell receptor)

2 - Co-stimulatory signal (engagement of CD28 w/B7 molecule)

NEEDS BOTH SIGNALS to ACTIVATE

31
Q

what is the role of CTLA-4 on co-stimulatory molecules

A

Acts as an “OFF” switch for immune response activation of Tcells by binding to B7 (co-stimulatory molecule)

32
Q

what are the 2 ways CTLA-4 can downregulate the immune response

A

1 - competively inhibit (co-stimulatory molecule) CD28 from binding to B7
2 - Bind to B7 which actively blocks

33
Q

CD28 and CTLA-4 both can bind to B7, what is the difference in signals if either bind

A

If CD28 binds to B7 = stimulate T cell activation

If CTLA-4 binds to B7 = inhibit T cell activation

34
Q

What is the difference b/w TH1 and TH2 helper T cells

A

TH1 - involved in cell mediated immunity, pro-inflammatory

TH2 - humoral immunity, anti-inflammatory

35
Q

What is the main generic role of cytokine IL-2

A

induces T cell proliferation/differentiation

36
Q

After antigen presentation, in order to amplify the T cell response a signal cascade will occurs to activate ______ which will induce IL-2

A

transcription factors NF-AT and NF-KB

37
Q

IL-2 is a cytokine that amplifies the T cell response by how much

A

1000 fold

38
Q

IL-2 once produced can cause 3 effects, what are they ?

A

1 - T cell proliferation
2 - Regulatory T cell development
3- -NK cell proliferation

39
Q

naive T cells can develop into Th1 or Th2 helper t cells, what drives the development of each

A

IL-12 drives dev. of Th1

IL-4 drives dev. of Th2

40
Q

what is the most important cytokine produced in response to Th1

A

IFN-gamma

41
Q

what is the most important cytokine produced in response to Th2

A

IL-4

Immunology (12 decks)

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