Exam 2: Dr. Pinchuk T-cell Mediated Immunity 2 Flashcards

1
Q

What does the third signal for Tc cell activation come from?

A

The APC in the form of IL-12

The cytokine strongly directs immune responses toward CD8-Tc cell response

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2
Q

What are cytotoxins? Examples?

A

Protein in the granules of cytotoxic T cells

Perforin, granzymes, and granulysin

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3
Q

What is the action of perforin on target cells?

A

Aids in delivering contents of granules into the cytoplasm of target cell

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4
Q

What is the action of granzymes on target cells?

A

Serine proteases, which activate apoptosis once in the cytoplasm if the target cells

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5
Q

What is the action of granulysin on target cells?

A

It has antimicrobial action and it can induce apoptosis

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6
Q

What cytokines can cytotoxins produce?

A

IFN-γ
LT-α
TNF-α

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7
Q

Because cytotoxins can produce cytokines, what does that men?

A

Cytotoxins can activate macrophages

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8
Q

What happens upon specific antigen recognition by cytotoxic T cells to cytotoxins?

A

The delivery of cytotoxins is aimed directly at the target cell

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9
Q

What is the life cycle of a Tc cell?

A

Naive CD8 T cell has antien recognition and goes through activation. Then, there is clonal expansion. These all occur in lymphoid organs. After that, the cell differentiates into a memory CD8 T cell or effector CD8 T cell in peripheral tissues.

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10
Q

What are the effector functions of the effector CD8 T cell?

A

Killing of infected target cells

Macrophage activation

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11
Q

What must T cells see in order to perform effector function?

A

Self-MHC

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12
Q

What are cytotoxic T cells?

A

Selective and serial killers of target cells

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13
Q

How does a cytotoxic T cell kill a target cell?

A

CTL recognizes virus-infected
CTL programs target cell to die
CTL moves to another target cell
First target cell dies

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14
Q

What is apoptotic cell death?

A

Programmed cell death

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15
Q

What T cells become natural regulatory T cells?

A

T cells specific for self antigen recognized in the thymus

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16
Q

What T cells become induced regulatory T cells?

A

T cells specific for self or commensal microbiota antigen recognized in presence of TGF-β in the periphery

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17
Q

What do cytokines produced by Treg cells do?

A

Inhibit other self-reactive T cells

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18
Q

What makes up regulatory T cells?

A

FOXP3+ CD4+ CD25+ Tregs

19
Q

What do regulatory T cells do?

A

Suppress the proliferation and IL-2 production of naive cells
Could suppress CD4 and CD8 cells

20
Q

What are the effector mechanisms of Tregs

A

Surface molecules have a constitutive expression of CTLA-4 which suppresses autoreactive T cells
Cytokines, IL-10, TGF-β are potent immunomodulatory cytokine that have anti-inflammatory function
Cytotoxins, perforin, gransyme A, and Fas-FasL

21
Q

What does CTLA-4 bind?

A

B7-1 and B7-2

22
Q

What is IL-10?

A

Potent immunomodulatory cytokine

23
Q

What are functions of IL-10?

A

Anti-inflammatory*
Down-regulates production of Th1-type cytokines
Decreases the expression of MHC class II and co-stimulatory molecules on DCs (tolerogenic state)*
Regulates the activation and function of mast cells
Regulates cytokine production by eosinophils
Directly suppresses T cell proliferation*

24
Q

What is the triadic function of TGF-β?

A

Acts as a SWORD to paralyze cell activation and differentiation to suppress immune response
Acts as a WAND to convert naive T cells into iTregs and Th17 to aid in their combat against inflammation and infection
Acts as a SHIELD to protect and maintain Tregs against apoptosis and destabilization when surrounded by inflammation and consistent stimulation

25
Q

What is the physiologic role of Th17 cells in the immune system?

A

Protective function against microbial pathogens

26
Q

What do Th17 cells represent?

A

A pro-inflammatory subset that contributes to autoimmunity and tissue damage

27
Q

What is the non-pathogenic subset of Th17 cells incapable of?

A

Promoting autoimmune inflammation and might even act anti-inflammatory

28
Q

What are highly pathogenic Th17 cells from?

A

Naive precursor cells that occur independently of TGF-β signaling in the presence of IL-23, IL-6, and IL-1β

29
Q

What is the function of Th17 cells?

A

To attract neutrophils and monocytes

30
Q

What are the Th17 and Treg developmental pathways like?

A

Reciprocally interconnected implicating a balance between both cell types which influences the outcome of the immune response

31
Q

What does the shared requirement of TGF-β and reciprocal regulation of the transcription factor between Th17 and Tregs provide?

A

Phenotypic and functional plasticity in both populations allowing differentiated cells to re-differentiate

32
Q

What kind of effect do Tregs have?

A

An antagonistic effect, which in failure contributes to the same diseases as excess Th17

33
Q

What does the Th17/Treg balance provide?

A

A basis for understanding the immunological mechanisms that induce and regulate autoimmunity and chronic inflammation

34
Q

When does inflammation occur?

A

FOXP3 is blocked by IL-6 and IL-21 which causes more Tregs (FOXP3)

35
Q

When does tolerance occur?

A

FOXP3 inhibits the expression of RORc causing Tregs and Th17 to be balanced

36
Q

When are T cells anergic?

A

In the absence of the co-stimulatory signal

37
Q

What are the immunologically privileged sites?

A
Brain
Eye
Testis
Uterus (fetus)
Hamster cheek pouch
38
Q

What is the most import form of tolerance?

A

Non-reactivity to self antigens

39
Q

What is it called when an antigen induces tolerance?

A

Tolerogen

40
Q

Describe cyctotoxic T cells

A

CD8 T cells

Kill infected cells by inducing apoptosis

41
Q

What is Th17 involved with?

A

Inflammation

42
Q

What do Tregs do?`

A

Either kill DCs or make them tolerogenic

43
Q

What are the mechanisms of central tolerance?

A

Negative selection in the thymus

Autoimmune regulator

44
Q

What are mechanisms of peripheral tolerance?

A

Absence of co-stimulatory signal
Immunological privileged sites
Regulatory T cells