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Inflammation and Wound Healing Exam 1 > T Cell Activation > Flashcards

T Cell Activation Flashcards

1
Q

what are the three signals required for T cell activation?

A
  1. TCR signalling
  2. co-stimulatory interaction
  3. cytokine signalling
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2
Q

what is the co-stimulator on T cells?

A

CD28

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3
Q

what happens during co-stimulatory signal engagement?

A

clonal activation results from the binding between CD-80/86 and CD28 molecule for T cell activation

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4
Q

what happens if CD-80/86 (APC) and CD28 molecule (T cells) do not bind?

A

no response

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5
Q

what are the co-inhibitors on T cells?

A

CTLA-4 and PD-1

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6
Q

what do the co-inhibitors CTLA-4 and PD-1 bind to which leads to inactivation or no response?

A

CTLA-4 engages CD-80/86 on APC = no response
PD-1 engages PDL1/2 on APC = inactivation (anergy)

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7
Q

what is the definition of anergy?

A

induction of non-responsiveness to further stimuli aka functional inactivation of cells

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8
Q

B7 is another name for what molecule?

A

CD80/86

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9
Q

the binding of B7 (APC) and CD28 is necessary for what? what happens if B7 binds with CTLA-4?

A

activation
anergy

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10
Q

What is ICOS-L expressed by and what is its activity?

A
  • expressed by B cells, some APCs, and T cells
  • maintenance of activity of differentiated T cells
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11
Q

what is the role of cytokines?

A

signaling molecules released by APCs or the surrounding environment, act as instructions that guide the T cell to differentiate into a specific subset.

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12
Q

what cytokines activate T helper 1, what is its role and what cytokines does it release?

A
  • IL-12, IFN-g, IL-18
  • macrophage activation and IgG production for defense against intracellular microbes associated with autoimmune disease/chronic infection
  • IFN-gamma, TNF
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13
Q

what cytokine activates T helper 2 , what is its role and what does it release?

A
  • IL-4
  • mast cell and eosinophil activation, IgE production and alternative macrophage activation against helminthic parasites involved with allergic diseases
  • IL-4, IL-5, IL-13
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14
Q

what cytokines activate T helper 17 , what is its role and what does it release?

A
  • IL-6, IL-23, TGF-B
  • organ-specific autoimmunity by neutrophilic and monocytic inflammation against extracellular bacteria and fungi
  • IL-17A, IL-17F, IL-22
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15
Q

what cytokines activate T follicular helper , what is its role and what does it release?

A
  • IL-6, IL-21
  • regulates affinity maturation of germinal center B cells
    -IL-4, IL-21
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16
Q

what cytokines activate T regulatory cell , what is its role and what does it release?

A
  • IL-2, TGF-B
  • suppresses immune response
  • IL-10, TGF-beta
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17
Q

what is polarization of response?

A

each T cell subset produces cytokines that amplify itself but inhibits the others so the response becomes increasingly polarized

18
Q

explain the steps of activation of macrophages through T helper 1 cells?

A
  1. APC produces IL-12
  2. transcription factor T-bet is activated
  3. T-bet induces naive T cells to differentiate into TH1 cells
  4. TH1 cells produce interferon-g which activates macrophages
19
Q

what do T helper 1 cells stimulate on APCs?

A

expreession of MHC molecules and CD-80/86 co-stimulatory molecules

20
Q

IFN-gamma stimulates macrophages to do what?

A

ingest microbes

21
Q

what happens when a macrophage is activated by IFN-gamma released by TH1 cells?

A
  • increased expression of MHC and co-stimulators
  • secretion of cytokines (TNF, IL-1, IL12, chemokines)
  • killing of phagocytosed bacteria
22
Q

what do T helper 1 cells and IFN-gamma mediate through B cells ?

A

antibody class switching and the production of IgG which binds to Fc receptors on phagocytes to enhance phagocytosis

23
Q

which transcription factor is activated when IL-4 binds to receptors on naïve T cells?

A

GATA3

24
Q

what does GATA3 do?

A

induce naive T cells to differentiate into TH2 cells, which are effective against worms

25
Q

TH2 cells produce both IL-4 and IL-13 that act together to activate and induce what?

A
  • mucus secretion
  • alternative activated macrophages (M2)
26
Q

TH2 cells mediate antibody class switching to ?

A

IgE (mast cell degranulation) and IgG

27
Q

TH2 cells also produce which cytokine that activates eosinophils ?

A

IL-5

28
Q

what do alternatively activated macrophages (M2) secrete, promote and inhibit?

A
  • secrete IL-10 and TGFB
  • promotes tissue repair
  • inhibits inflammation and microbicidal activity of classically activated macrophages (M1)
29
Q

which transcription factor induces naive T cells to differentiate into TH-17 cells?

A

ROR-gamma-t

30
Q

what does T helper 17 cell induce and produce?

A
  • induces inflammation
  • produces IL-17, IL-22, and pro inflammatory cytokines (TNF, IL-1, IL-6)
31
Q

what do T helper 17 cells recruit ?

A

neutrophils and some monocytes

32
Q

what do T helper 17 cells help to increae?

A
  • barrier function like in the GI tract
    -production of anti-microbial peptides for fungal and bacterial infections
33
Q

T regulatory cells contain CD4, CD25 and T suppressor cells that inhibits or turns down what?

A

T cell response

34
Q

what is the transcription factor of a regulator T cell?

A

FOXP3

35
Q

what activates FoxP3?

A

TGFB and antigen specific T cell receptors

36
Q

T reg expresses which inhibitory molecule? what does it do?

A

CTLA-4, inhibits proliferation and activation of CD4 and CD8 cells

37
Q

which T helper cells engage with cytotoxic T lymphocytes and how?

A
  • T helper 1
  • by CD40/40L to provide interleukin-2 for proliferation
38
Q

after targets are eliminatedm, most B/T cells die but a small portion survive and become what?

A

memory cell populations that have IL-7 receptors and protein CD27

39
Q

in the absence of antigen but presence of what cytokines cause effectors cells to become memory cells?

A
  • IL-7 and IL-15
40
Q

maintanence of memory cells is dependent on what? but does not require what?

A
  • cytokines
  • antigen recognition
41
Q

what are superantigens and what do they bind?

A
  • microbial products that non-antigen specifically stimulate the T lymphocytes in an uncontrolled manner when present in low concentrations, resulting in fever, shock, and death
  • MCH class II and T cell receptors

Inflammation and Wound Healing Exam 1 (15 decks)

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