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Phar 504 > Lymphoctye activation: T cell > Flashcards

Lymphoctye activation: T cell Flashcards

1
Q

What is the percentage break down of T lymphoctyes that circulate and stay in one place

A

50% vs 50%

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2
Q

What are the three type of mature T lymphoctes

A

naive, effector, memory

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3
Q

What is the function of naive lymphocytes, where are they located

A

antigen recognition, reside in lymph nodes

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4
Q

What is the function of effector T lymphocytes

A

perform functions required to eliminate microbes in periphery

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5
Q

What is the function of memory T lymphocytes

A

functionally silent cells but mount rapid responses to antigen challenge (secondary response)

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6
Q

What is a key difference in T cells and B cells

A

T cells require antigen presentation by other cells vs B cells that recognize whole antigens on their own; antigen peptides vs antigen parts

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7
Q

What is the function of helper T cells, what protein causes activation

A

Cytokine production that leads to T cell differentiation, B cell growth, macrophage activation, MHC 2 restricted activation

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8
Q

What is the function of cytotoxic T cells, what protein cause activation

A

Lysis of virus and tumor infected cells, MHC 1 restricted activation

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9
Q

Which cells present MHC 1 protein, MHC 2

A

all nucleated cells, antigen presenting cells

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10
Q

What is the difference in antigen that would determine MHC class

A

MHC 1 -> endogenous protein antigen catabolized in the cytoplasm MHC 2-> exogenous protien antigen catabolized in acid compartment

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11
Q

What are the functions of antigen presenting Cells

A

process and present antigen to T-lymphocytes, provide secondary stimuli to the T cell required for achievement of full T cell response

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12
Q

T/F: APCs can express MHC 1 and MHC 2

A

True

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13
Q

What is the most key feature of dendritic cells. what are other important features

A

Most efficient in initiating adaptive immune response, travel from periphery (site of infection) to lymph nodes to activate naive T cells/express high levels of costimulatory and adhesion molecules

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14
Q

What is the most key feature of macrophages, what are other important features

A

provide continuous stimuli to keep T cells going at the periphery, have low levels of MHC 2 at first but cytokine stimulation will lead to higher levels of MHC 2

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15
Q

Where does a large number of APC interactions with Naive T cells occur

A

Lymph nodes

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16
Q

What part of the T cell interacts with the APC

A

TCR

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17
Q

T/F: It is sufficient and necessary to have and interaction between the TCR and MHC 2 of APCs

A

False: it is necessary but not sufficient to propagate a signal

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18
Q

What are the components needed for full T cell activation

A

Co-receptor (CD4 or CD8), costimulatory pairs, adhesion molecules

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19
Q

What are costimulatory pairs, are they essential for activation of naive T cells

A

clustered intracellular signaling molecules around the TCR allowing activation signal to dispatched to the nucleus, yes

20
Q

What are the two most important costimulatory pairs (for this class) where cell types are they located on

A

B7 (infected cells)/CD28 (T cells). CD40L (T cells)/CD40 (APCs)

21
Q

T/F: Effector and memory T cells require less co-stimulation

A

True

22
Q

What are processes that occur due to B7/CD28 binding

A

mobilize kinases and other signaling proteins around TCR, increase half life of cytokine mRNA molecules ( leads to 100x more cytokines produced), increase T-Cell proliferation, prevent apoptosis

23
Q

What are processes that occur due to CD40/CD40L binding

A

On APC: promote up regulation of MHC and other costimulatory molecules/increase longevity of dendritic cells by increasing production of IL-12, For B cell: Promotes B cell proliferation/promote Ig class switching

24
Q

What is the function of adhesion molecules

A

form an outer ring, stabilizing the T cell-APC contact and assist in migration of T cell to sites of inflammation and infection

25
Q

What is the most important membrane kinase for T cell activation

A

Zap-70

26
Q

What is the enzyme that is the result of the IP3 pathway, what transcription factor does it release

A

Calcineurin, NFAT

27
Q

What is the enzyme that is the result of the DAG pathway, what transcription factor does it release

A

PKC, NF-kB

28
Q

What is the enzyme that is the result of the Ras pathway, what transciption factor does it release

A

ERK/JNK, AP-1

29
Q

What does NFAT lead to, what is the purpose of

A

Calcineurin, increase synthesis of IL-2 (T cell growth factor)

30
Q

What are the three signals needed for T cell activation

A

1) Antigenic signal 2) Co-stimulatory signal 3)Cytokine signal

31
Q

T/F: Once activated lymphocytes will plofierate to build up clones with the same antigen specificity and after doubling its numbers every 6 hours for 3-4 days differentiation occurs

A

True

32
Q

Once activation ends due to disengagement what are changes the T cell will make

A

Upregulation of chemokine receptors and adhesion molecules in order to migrate to the affected tissue

33
Q

What is the function of CD8 T cells, CD4 T cells

A

destroy antigen carry target cell, secrete cytokines

34
Q

How does CD4 T cells know what cytokines to produce

A

The presence of cytokines in the environment during activation drives the differentiation

35
Q

What cytokine leads to T Helper 1 cells, what APC releases what cytokine for this differentiation, what cytokine do Th1 produce,

A

IL-12, dendritic cells, IFN-gamma and IL-2

36
Q

What cytokine leads to T Helper 2 cells, what APC release what cytokine for this differentiation, what cytokine to Th2 produce

A

IL-4, macrophages, IL-4 and IL-5

37
Q

What type of immunity does T helper 1 cells assist in, where does its actions take place

A

Cell mediated immunity ( increase phagocytosis, cytotxicity), activated endothelium tissue

38
Q

What type of immunity does T helper 2 cells assist in, where does its actions take place

A

Antibody mediated immunity (IgE,IgA eosinophil recuitemnt, mast cell recruitment)

39
Q

T/F: T helper 2 cells cause macrophage activation

A

False: T helper 1 cells are involved in macrophage activation

40
Q

What occurs in Helper T cell independent activation of CD8+ T cells

A

TCR interacts with MHC 1 leading to activation and proliferation capable of killing cells

41
Q

What occurs in Helper T cell dependent activation of CD8+ T cells

A

APC interaction with CD4+ cell leads to release of IL-2 that induces CD8+ activation resulting in destruction of target cells expressing MHC 1 associated antigenic peptides

42
Q

In T helper cell dependent activation what is needed for the CD8+ T cell to recognize the correct cells to destroy

A

The same antigenic peptide and the same MHC protein

43
Q

What are the two major mechasim for cytotoxic kills

A

cytotoxins (perforin and granzymes) Fas/FasL

44
Q

What is the mechanism of action for perforin, granzymes

A

poke holes in the cell membrane induce apoptosis

45
Q

How does Fas cause cell death

A

FasL (CD8+) binds Fas (infected cell) causing caspases to be release inducing apoptosis

46
Q

T/F: CD8+ T cell memory T cells can be activated by dependent and independent T helper cell activation

A

False: CD8+ T cell memory cells will only be generated via T helper dependent activation

47
Q

Negative selection can prevent hyper activation of immune response through what mechanism

A

CTLA4 binds to B7 more than CD28 inhibiting the T cell response

Phar 504 (34 decks)

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