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Immunology > T-Cell Mediated Immunity > Flashcards

T-Cell Mediated Immunity Flashcards

1
Q

What are the locations of immature dendritic cells and mature dendritic cells?

A
  • Immature: peripheral tissue looking for pathogen
  • Mature: lymph nodes presenting antigen via MHC
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2
Q

Why are dendritic cells confined to the cortex of lymph nodes after migrating from the periphery?

A

Because that is where naive T-cells congregate

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3
Q

Are macrophages or dendritic cells the primary APNs?

A

Dendritic

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4
Q

Dendritic cells are only capable of activating ______ cells

A

Naive CD8 T-cells

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5
Q

What is the difference between receptor-mediated endocytosis and macropinocytosis?

A
  • RME: Pathogen binds to receptor which triggers endocytosis
  • MPC: endocytosis for pathogens too large to bind to receptor
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6
Q

Why are there more restrictions on CD8 activation compared to CD4?

A

CD8 cells are the killer cells

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7
Q

Identify where the dendritic cells are located based on their morphology

(MHCII = Green ; Lysosomal protein = Red)

A
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8
Q

What dendritic cell surface receptor binds pathogen to activate said cell?

A

TLR

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9
Q

What is the function of CCR7 on the surface of dendritic cells?

A
  • Binds to chemokine CCL21
  • Causes dendritic cells to exit the lymph and make their way toward the periphery
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10
Q

Which lymphocyte is the most abundant in blood vessels?

A

Naive T cells

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11
Q

Describe the two modes of entry for T-cells into lymph nodes.

A
  1. From the blood via high endothelial venules (HEVs)
  2. From the lymphatics via afferent lymphatic vessels
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12
Q

Each naive T cell recirculates from blood through a lymph node and back to blood every ______.

A

12-24 hours

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13
Q

What are quiescent T-cells?

A
  • Small, undividing, unactivated T-cells
  • Have condensed chromatin, little cytoplasm, and little RNA/protein synthesis
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14
Q

What is “homing” in regard to T-cell migration?

A

Process by which T-cells leave the bloodstream and enter the T-cell zone of lymph nodes

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15
Q

Which cytokines secreted by stromal cells and dendritic cells guide T-cell homing? (2)

A
  • CCL21
  • CCL19
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16
Q

Which cell surface protein of T-cells binds CD34 and GlyCAM-1 on HEVs to facilitate attachment to endothelial cells.

A

L-selectin

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17
Q

LFA-1 on T-cells binds to _______ on HEVs to strengthen attachment to endothelial cells.

A

ICAM-1 and ICAM2

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18
Q

ICAM-1 and ICAM-2 on dendritic cells bind to _____ on T-cells

A

LFA-1

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19
Q

ICAM3 on the surface of T-cells binds to _____ on dendritic cells.

20
Q

CD2 on the surface of T-cells binds _____ on dendritic cells to increase adhesion

21
Q

What is the function of sphingosine 1-phosphate (S1P)?

A
  • Guide T-cells out of the lymph node if they don’t encounter antigen
  • Via gradient in the medulla
22
Q

Activated T-cells express _____ to sequester S1P receptors back into themselves

23
Q

Explain the events that IMMEDIATELY occur when a naive T-cell recognizes a peptide:MHC complex? (not an enzymatic cascade)

A
  • LFA-1 / ICAM interactions are strengthened by conformational changes
  • T-cells proliferate (clonal expansion)
  • Dendritic cells maintain contact with clones as a “nursery” for propagation of T-cells
24
Q

What is the function of CD28 on the T-cell surface?

A

Bind to B7 on dendritic cell to act as a co-stimulator when TCR binds MHC.

25
Q

What are the two complexes that form the synapse between T-cells and dendritic cells?

A
  • c-SMAC - central supramolecular activation complex
  • P-SMAC - peripheral supramolecular activation complex
26
Q

TCR/MHC activation induces phosphorylation of _____ and _____.

A
  • CD3 cytoplasmic tails
  • ζ chain
27
Q

What are ITAMs?

A
  • Immunoreceptor tyrosine-based activation motifs
  • tyrosine residues that allow for phosphorylation (specifically for CD3 and the ζ chain)
28
Q

What is the function of Lck in T-cell activation?

A
  • Tyrosine kinase
  • Phosphorylates CD3 and ζ chain ITAMs, as well as ZAP-70
29
Q

What is the function of ZAP-70?

A
  • Binds phosphorylated tyrosines of the ζ chain
  • Necessary for initiating the major T-cell signaling pathway
30
Q

ZAP70 initiates activation of various transcription factors that induce T-cell proliferation, differentiation, and effector function. Which transcription factors are they? (3)

A
  1. NFAT
  2. NF-κB
  3. AP-1
31
Q

NFAT, NF-κB, and AP-1 activation ultimately lead to the activation of _____, a growth cytokine critical for T-cell activation.

32
Q

Name the immunosuppressive drugs that target IL-2 (3).

A
  1. Cyclosporin A
  2. Tacrolimus (FK506)
  3. Rapamycin
33
Q

True or false. Self-antigen is not expressed in the thymus.

34
Q

Absence of CD28 in T-cells results in _____

A
  • Anergy
  • Will not respond to external stimuli
35
Q

What happens to a T-cell that recognizes self-antigen?

36
Q

What are the functions of the following helper T-cells?

  1. TH1
  2. TH17
  3. TH2
  4. TFH
  5. Treg
A
  1. TH1 - activation of macrophages
  2. TH17 - enhance neutrophil response
  3. TH2 - Activate cellular antibody response to parasites
  4. TFH - Activate B cells; maturation of antibody response
  5. Treg - Supppress other effector T cells
37
Q

What are the master regulators (or defining transcription factors) of the following helper T cells?

  1. TH1
  2. TH17
  3. TH2
  4. TFH
  5. Treg
A
  1. TH1 - T-bet
  2. TH17 - RORγT
  3. TH2 - GATA3
  4. TFH - Bcl6
  5. Treg - FoxP3
38
Q

Which of the following types of helper T cells remains in the secondary lymph tissue?

  1. TH1
  2. TH17
  3. TH2
  4. TFH
  5. Treg
39
Q

Activated T-cells no longer express L-selectin. What is the consequence of this?

A

They can no longer enter secondary lymph tissue

40
Q

VLA-4 is only expressed by activated T-cells, allowing them to leave blood and enter tissues by binding to _____ expressed on endothelial cells of infected tissue.

41
Q

True or false. Only CD4 T-cells can produce cytotoxins.

A

False. Only CD8 T-cells can

42
Q

What is the function of IFN-γ produced by CD8 T-cells?

A
  • Inhibition of viral replication in infected cells
  • Increases processing of viral antigen and presentation
  • Activation of local macrophages
43
Q

What is the function of perforin, granulysin, and serglycin?

A
  • Make a pore on target cell
  • Deliver granzymes
44
Q

What is the function of granzymes?

A

It is a serine protease that initiates cascade of proteolytic cleavage and activation of nucleases to induce apoptosis of infected cells

45
Q

What proteins are present in the p-SMAC region of the dendritic-T cell synapse?

A
  1. LFA-1
  2. ICAM-1
  3. Talin
46
Q

What proteins are present in the c-SMAC region of the dendritic-T cell synapse?

A
  1. TCR
  2. CD2
  3. CD4
  4. CD8
  5. CD28
  6. PKC-θ

Immunology (13 decks)

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