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Immunology > 8-T Cell Mediated Immunity > Flashcards

8-T Cell Mediated Immunity Flashcards

1
Q

Which cells carry bacterial Ag’s from the tissues to the secondary lymphatic tissues?

A

Dendritic cells

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2
Q

When do dendritic cells turn from immature to mature cells?

A

When they have degraded a bacteria and presented the Ag’s on their MHC-I and MHC-II molecules

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3
Q

Why do dendritic cells have both MHC-I and MHC-II molecules?

A

Because they are both a professional antigen-presenting cell (which have MHC-II) and nucleated (all nucleated cells in the body (every cell except RBC’s) have MHC-I)

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4
Q

What happens to the dendrites of dendritic cells when they mature?

A

They become super awesome

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5
Q

Where do dendritic cells carry Ag’s to from infections on the skin?

A

lymph nodes

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6
Q

Where do dendritic cells carry Ag’s to from infections in the blood?

A

spleen

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7
Q

Where do dendritic cells carry Ag’s to from infections in the lungs?

A

tonsils or BALT

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8
Q

Where do dendritic cells carry Ag’s to from infections in the gut?

A

GALT

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9
Q

How do naive T cells get to the lymph node from the blood? (generally)

A

They bind to the vessels endothelial cells of the high endothelial venules (HEV) and squeeze through to the lymph node

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10
Q

What is another way a naive T cell can get to a lymph node? (other than through the blood)

A

Through the lymph from passing through a prior lymph node

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11
Q

What are the 2 things that could happen to a naive T cells once it enters a lymph node?

A
  1. It could find the Ag:MHC match to its TCR and begin to proliferate or 2. not find a match and be sad.
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12
Q

What chemokines attract a naive T cell in the blood to the HEV?

A

CCL21 and CCL19

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13
Q

What does the L-selectin on the naive T cell bind to on the HEV?

A

CD34 and GlyCAM-1

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14
Q

Binding of the L-selectin of the T cell to the CD34 and GlyCAM-1 causes what?

A

The slowing down of the T cell in the blood.

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15
Q

What additional interaction occurs between the T cell and the HEV to add to the strength of the interaction?

A

The LFA-1 receptors on the T cell bind to the ICAM-1 and 2 on the HEV

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16
Q

How does the dendritic cells in the lymph node enhance the strength of the bond of between the naive T cell?

A

They express LFA-3 which binds to the CD2 on the T cell

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17
Q

What does the TCR bind to on the dendritic cell?

A

The Ag that is being presented by the MHC

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18
Q

What are the 2 proteins involved in the costimulatory complex between the T cell and the dendritic cell?

A

CD28 of the naive T cell and B7 of the dendritic cell

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19
Q

What is the point of the costimulatory signal?

A

Just the binding of the TCR to the Ag and the CD4 to the MHC-II isn’t enough to activate the T cell, therefore we need a second costimulus to activate the naive T cell.

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20
Q

What is the function of CTLA-4?

A

It’s secreted by the T cell and it inhibits the CD28 by binding to the B7 receptor. This inhibits the costimulatory signal and dampens down the activation and limits cell proliforation.

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21
Q

What are functions of Langerhans cells?

A

They will uptake and process antigens just like regular dendritic cells?

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22
Q

What makes Langerhans cells different than dendritic cells in the lymph node?

A

Theyre called interdigitating cells- in addition to having B7 and MHC, they increase the expression of adhesion molecules, which attracts naive T cells towards them.

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23
Q

Where in the lymph node are the dendritic cells?

A

T cell areas

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24
Q

Where in the lymph node are the macrophages?

A

Eeerywhere

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25
Q

What is the function of dendritic cells?

A

activate T cells

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26
Q

What are the functions of macrophages?

A

There are lots- eat stuff, be an APC, kill lymphocytes that are gonna die, and have TLR’s for innate immunity

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27
Q

Why is Listeria so super goofy?

A

Because it escapes the phagosome of macrophages and can grow in the cytoplasm of the macropahge

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28
Q

How does the body kill Listeria?

A

Its growth in the cytoplasm triggers CD8 Tc cells to come and kill it.

29
Q

What is the purpose of the CD4 molecule?

A

It checks that the Ag that is being presented to the TCR is from a MHC-II

30
Q

Which proteins on the TCR transmit the signal to the intracellular portion upon binding of the Ag?

A

CD3

31
Q

What do the cytoplasmic tails of the CD3 proteins contain?

A

ITAMs

32
Q

What do the ITAMs associate with?

A

Protein tyrosine kinases

33
Q

What do the protein tyrosine kinases do on the ITAMs?

A

They phosphorylate them so that enzymes and other molecules can bind and then alter gene expression.

34
Q

What do the cytoplasmic portions of the CD4 molecules associate with?

A

A protein tyrosine kinase called Lck

35
Q

What does Lck do?

A

It phosphorylates a protein kinase called ZAP-70

36
Q

What does ZAP-70 do?

A

binds to the tails of the CD3 receptors and initates the intracellular pathway

37
Q

Question: patient presents with immunodeficiency symptoms. There are normal serum levels of T cells, but it found that the signaling mechanism is defective when an Ag is presented by an MHC-II molecule. What key enzyme must be missing in the T cell?

A

ZAP-70

38
Q

How does activation of ZAP-70 lead to cell division, proliferation and differentiation of effector T cells (generally)?

A

IT initiates a series of reactions that leads to the PLC pathway (kinda like the Gq pathway) which activates transcription factors

39
Q

When is IL-2 released from the T cells?

A

when the T cell becomes activated from binding of an Ag to the TCR

40
Q

What is the function of IL-2?

A

It binds to the IL-2R’s on the SAME cell and drives colonal expansion of the activated cell

41
Q

What subunit gets added to the IL-2R on the T cell surface to activate it?

A

The α subunit is added to the γ and β dimer, thus activating the cell.

42
Q

When is the IL-2R α subunit synthesized?

A

The same time IL-2 is synthesized- when the T cell is activated

43
Q

What happens when an Ag:MHC binds to a TCR but there is NOT any binding of CD28 to B7?

A

Lack of costimulation leads to anergy of the cell

44
Q

What happens during T cell anergy?

A

They are unable to make IL-2 and become indefinitely nonresponsive to Ag stimulation.

45
Q

What are the 2 main cytokines of TH1?

A

IL-2 and interferon (IFN)-γ

46
Q

What do IL-2 and interferon (IFN)-γ do?

A

macrophage activation, inflammation, and the production of opsonizing antibodies

47
Q

TH1 is said to activate what type of immunity?

A

Innate (cell-mediated) immunity

48
Q

What are the 2 main cytokines of TH2?

A

IL-4 and IL-5

49
Q

What are the main functions of IL-4 and IL-5?

A

They lead to B cell activation and differentiation

50
Q

What type of immunity does TH2 lead to?

A

Adaptive (humoral) immunity

51
Q

What is the main determining factor as far as which type of leprosy an indiviudal might suffer from?

A

Whether the immune response to M. leprae is strongly biased towards a TH1 or TH2 response

52
Q

What are the clinical manifestations of a TH1-biased response to leprosy?

A

it enables the macrophages to supress the bacterial growth- disease progresses slowly and the pts usually survive.

53
Q

What is TH1-biased leprosy called?

A

Tuberculoid leprosy

54
Q

What are the clinical manifestations of a Th2-biased response to leprosy?

A

Since there can’t be Ab’s made to the intracellular pathogen, there can’t be an immune response- massive tissue destruction and soon death.

55
Q

What is Th2-biased leprosy called?

A

Lepromatous leprosy

56
Q

What are the 3 ways CD8 cells can be activated?

A

(1) High levels of B7 expresison fo dendritic cells. (2) CD4 activates the APC which activates the CD8. (3) APC makes CD4 make IL-2 which activates neighboring CD8

57
Q

Why is activation of effector T cells different than naive T cells?

A

Cuz they can respond to their specific Ag w/o the need for co-stimulatory signals.

58
Q

What type of cells do CD8 cells kill?

A

Cells that have become overwhelmed by intracellular infection.

59
Q

What are the 2 things that the CD8 cells secrete?

A

Lytic Granules (they have a lot of bad stuff in them) and IFN-γ for macrophage recruitment

60
Q

What are the proteins in the CD8 cytotoxic granules that punch holes in the membrane of cells, inducing apoptosis?

A

Perforin and Granulysin

61
Q

What is expressed on the surface of CD8 cells that signals the target cell to undergo apoptosis?

A

Fas ligand

62
Q

What are the 2 things released from the TH1 cell that activate macrophages?

A

CD40 and TNF-α

63
Q

Why is TH2 cells anatonists to Th1?

A

They act like a safety mechanism to make sure there isn’t an extreme cell-mediated immune response

64
Q

What is the main cytokines released from TH2 cells that inhibit TH1 cells?

A

IL-10 and IL-4

65
Q

What is the fxn of IL-3 from Th1?

A

induces macrophage differentiation in the bone marrow

66
Q

Why do granulomas form?

A

They form when microbes resist macrophage eating, so they wall off and form a big mass of gross pathogens.

67
Q

What does the CD40 ligand get released from TH2 cells?

A

When they are activated from B cells when B cells present an Ag that the TCR can bind to

68
Q

What does the CD40 ligand from TH2 do to B cells?

A

The B cells have a CD40R which drives teh resing B cell into the cycle of cell division.

69
Q

What is the function of regulatory CD4 T cells?

A

They suppress the activation of naïve autoreactive CD4 and CD8 cells that have the potential to attack the body’s tissues

Immunology (11 decks)

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