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SFM Final > T Cell Mediated Immunity > Flashcards

T Cell Mediated Immunity Flashcards

1
Q

What is the only cell that can activate naive T cells?

A

Dendritic cells

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2
Q

What kind of T cells activate B cells and macrophages?

A

CD4+ T cells

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3
Q

What is the purpose of CCR7 in DCs?

A

It helps localize the activated DC to lymphatic endothelium.

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4
Q

Where do naive T cells enter the lymph nodes from?

A

High endothelium venules

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5
Q

What two T cell transmembrane proteins are found on both helper and cytotoxic T cells that play a key role in signal transduction?

A

CD3 and ζ chain

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6
Q

What is the ligand for the T cell surface molecule, CD28?

A

CD80 (B7), found on APCs

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7
Q

What are the inhibitory molecules found on the surface of T cells?

A

CTLA-4 and PD-1

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8
Q

What does CTLA-4 inhibit?

A

CD80 (B7), which is normally activated by CD28

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9
Q

What molecules are upregulated as a result of T cells and APCs binding their the MHC/TCR complexes?

A

CD40L expression is upregulated in T cells; CD40 is constitutively expressed on APCs. CD80 (B7) expression is upregulated on APCs; CD28 is constitutively expressed on T cells.

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10
Q

Describe the initiation of the intracellular signaling cascade in T cells following the formation of the immunologic synapse.

A

Immunoreceptor tyrosine-based activation motifs (ITAMs) are activated. Lck phosphorylates and activates ZAP-70 on ζ chain.

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11
Q

What membrane proteins are upregulated as a result of T cell activation?

A

CD40L and CD25 (IL-2R α chain)

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12
Q

What is the purpose of IL-2 in T cells?

A

It is an autocrine signal that triggers proliferation and differentiation.

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13
Q

The expression of what molecule prevents activated T cells from migrating out of the lymph node? What does it bind to?

A

CD69 binds to S1PR

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14
Q

What are the main targets for Th1 cells?

A

Macrophages and B cell class switching to IgG. Also CD8+ cloning and activation.

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15
Q

What are the main targets for Th2 cells?

A

Eosinophils/Mast cells in response to allergens and helminths, and B cell class switching to IgE. Also supports alternative macrophage development.

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16
Q

What are the main targets for Th17 cells?

A

Neutrophils and barrier function in tissue cells

17
Q

What is the main target for Tfh cells?

A

B cells for antibody production

18
Q

Describe T regulatory cells (Tregs). What do they express and secrete?

A

A type of CD4+ cells that constitutively express CTLA-4 and CD25. They secrete IL-10 and TGF-β. Uses novel transcription factor FOXp3.

19
Q

Describe gamma delta T cells.

A

Found in high numbers in gut mucosa. Limited diversity of peptides recognized, but can recognize non-protein Ag and it does not require MHC presentation.

20
Q

What do Th1 cells proliferate in response to? What do they secrete?

A

Responds to IL-12 and IFN-γ. Secretes IL-2 and IFN-γ.

21
Q

What is the novel transcription factor for Th1 cells?

A

T-bet

22
Q

How do Th1 cells affect APCs once activated?

A

They stimulate HLA II and B7 (CD80) expression

23
Q

What do Th2 cells proliferate in response to? What do they secrete?

A

Responds to IL-4. Secretes IL-4, IL-5, IL-13.

24
Q

What is the novel transcription factor for Th2 cells?

A

GATA-3

25
Q

What is the difference between classically activated and alternatively activated macrophages?

A

Classic: activated by Th1, leads to phagocytosis and killing of many bacteria and fungi.
Alternative: activated by Th2, leads to anti-inflammatory effects, wound repair, and fibrosis.

26
Q

What do Th17 cells proliferate in response to? What do they secrete?

A

Responds to IL-1 and IL-6. Secretes IL-17 and IL-22.

27
Q

What is the novel transcription factor for Th17 cells?

A

RORγt

28
Q

What is the purpose of CD44 in T helper cells?

A

It helps with cell adhesion and migration into peripheral tissues.

29
Q

What are the two main killing mechanisms for cytotoxic T cells?

A
  1. Cytotoxins: granzymes and perforin

2. FasL and Fas (CD95) induction of apoptotic pathways

30
Q

What are NK cells enhanced and inhibited by?

A

Enhanced by IFN-α, IFN-β, and IL-2. Inhibited by HLA I.

31
Q

What are the surface markers for NK cells?

A

CD16 and CD56

32
Q

What do memory T cells increase the expression of in order to prevent apoptosis?

A

Bcl-2

33
Q

What is the role of the PD-1 receptor?

A

Expressed on T cells, B cells, and myeloid cells. Leads to negative regulation of T cells.

34
Q

Which interleukins are required for the survival of memory T cells?

A

IL-7 and IL-15

35
Q

What happens to CD4+ and CD8+ cells during chronic viral infections?

A

They become exhausted and are unable to respond to the virus.

36
Q

What is toxic shock syndrome’s (TSS) affect on the immune system?

A

The toxin released acts as a superantigen and leads to nonspecific T cell activation. Binds to β chain of TCR.

SFM Final (5 decks)

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