Exam 2: How T Cells Work (Ch.6)

Question 1

What are the two jobs of Helper T Cells?

Answer 1

1. remain in blood and lymph nodes providing help for B cells and CTLs
2. Leave the blood and enter battle sites providing help for soldiers on the front line

Question 2

What are communication proteins for the immune system and others and are used to drive the immune system in a particular direction?

Answer 2

cytokines

Question 3

How do Helper T cells send the signal “for help” out?

Answer 3

cytokines

Question 4

What type of cells provide “education” regarding type of invader and location of invader?

Answer 4

dendritic cells

Question 5

What are the “two signals” that provide information to dendritic cells so they know what’s going on?

Answer 5

1. PRR’s (pattern recognition receptors), such as TLRs on dendritic cells recognize PAMPs (pathogen ass. molecular patterns) on invaders
2. Cytokines produced by cells in the area under attack

Question 6

What are two examples of PRRs on dendritic cells that recognize PAMPs on invaders?

Answer 6

• TLR4 recognizes LPS

- TLR3 recognizes dsRNA

Question 7

What information do cytokines produced by cells in the area under attack provide the dendritic cell with? (3)

Answer 7

1. indicate particular location in body (where)
2. diff pathogens elicit diff cytokines (type/what))
3. cells from diff areas of body make diff combinations of cytokines

Question 8

What should we think of cytokines as?

Answer 8

address for anatomical location (where) and pathogen identity (what)

Question 9

T/F. Cytokines released by dendritic cells convince T cells to express specific sets (profiles) of cytokines.

Answer 9

True — we give these T cells diff names based on their cytokine profile (Th1, Th2, Th9, Th17, Th22, Treg, Tfh)

Question 10

What type of T helper cell is used for Viral or Bacterial Attack?

Answer 10

Th1 Helper T Cells

Question 11

What do Th1 Helper T cells react to, and why type of cytokines do they release?

Answer 11

viral and bacteria attacks

Classical Cytokines

• TNF
• IFN-gamma
• IL-2

Question 12

What is the goal of Th1 Helper T cells?

Answer 12

• activate macrophages and natural killer cells

Question 13

What will IFN-gamma, release by Th1 Helper T cells do?

Answer 13

(viral or bacteria attack)

• keeps macrophages active
• tells B cells to make IgG3 (opsonizes viruses and bacteria and fixes complement)

Question 14

What does IL-2, released by Th1 Helper T cells do?

Answer 14

(viral and bacteria attack)

• recharges NK cells
• stimulates proliferation of CTLs, NK cells, and more TH1 cells

Question 15

What type of Helper T cells is used for a parasitic attck or food contaminated with pathogenic bacteria?

Answer 15

Th2 Helper T cells

Question 16

What do Th2 Helper T cells respond to? What type of cytokines do they release?

Answer 16

parasitic attack or food contaminated with pathogenic bacteria–> intestines under attack

• IL-4
• IL-5
• IL-13

Question 17

What is the goal of the three cytokines released by Th2 Helper T cells in response to a parasitic attack?

Answer 17

IL-4 –> growth factor to proliferate T cells and for B cells making IgE

IL-5 –> causes B cells to make IgA (antibacterial in the GI)

IL-13 –> stimulates mucus in intestine

Question 18

What type of T Helper cell is used from fungal attack and muscosal barriers?

Answer 18

Th17 Helper T cells

Question 19

What do Th17 T Helper cells respond to? an what cytokines do they release?

Answer 19

fungal attack and mucosal barriers

IL-17
IL-21

Question 20

What do the two cytokines released by Th 17 T Helper cells in response to a fungal and muscoal barriers attack do?

Answer 20

IL-17 –> recruits massive numbers of neutrophils to the area

IL-21 –> causes growth of more Th17 cells

influence production of opsonizing antibody

Question 21

What do Dendritic cells make that cause help T cells to make Th17 cytokines?

Answer 21

dendritic cells make TGF-beta and IL-6

Question 22

What do Th1 Helper T cells recruit?

Answer 22

(ass. with viral and bacteria attack)
- macrophages
- CTLs
- NK cells

Question 23

What do Th2 Helper T cells recruit?

Answer 23

(ass. with parasitic attack and intestines under attack)
- B cells
- IgA and IgE production

Question 24

What do Th17 Helper T cells recruit?

Answer 24

(ass. with fungal attack and mucosal barriers)
- neutrophils
- opsonizing Ab production

Question 25

What type of Helper T cells are waiting until they enter the tissue to determine Th type based on cytokines present and are non committed T cells and will change based on cytokine env.?

Answer 25

Th0 Helper T cells

Question 26

T/F. Cytokines have a very wide range on where can have impact.

Answer 26

False-- they have a very limited range (local impact only)

Question 27

Once a helper T cell starts making a certain type of cytokine profile, what is it considered?

Answer 27

it is committed

Question 28

What do cytokines released by helper T cells promote and inhibit?

Answer 28

Promote--> their Th subset Inhibit --> other Th subsets Ex: Th2 cells make IL-10 which inhibits production of Th1 subset

Question 29

What are Superantigens?

Answer 29

``` are a special class of T-cell activators: = viral/bacterial proteins that bind to specific regions of TCRs and class MHC II molecules ``` produce dramatic cytokine secretion by large proportion of inappropriately activated T cells

Question 30

What are a special class of T-cell activators that are viral or bacterial proteins that bind to specific regions of TCRs and class II MHC molecules and produce dramatic cytokine secretion by large proportion of inappropriately activated T cells?

Answer 30

Superantigens (over activation of T helper cells) Ex: TSST-- toxic shock syndrome toxin

Question 31

What does a Naive CTL (killer t cell) need for activation?

Answer 31

a licensed dendritic cell presenting cognate Ag on a MHC I and co-receptors and co-stimulation occur

Question 32

How do we license a dendritic cell, which has the ability to activate a naive CTL?

Answer 32

- T-helper cell help - dendritic cell directly recognizes PAMPs - "license" the dendritic cell to present exogenous protein to MHC1

Question 33

How do Helper T cells control the size of the response?

Answer 33

by dictating (through cytokines) the number of killer T cells being activated

Question 34

What are the two ways the Killer T cells kill?

Answer 34

1. CTL delivers a package with perforin and granzyme B | 2. CTL connects its Fas ligand to the Fas protein on the target cell

Question 35

What occurs when a Killer T cell (CTL) delivers a package with perforin and granzyme B?

Answer 35

- perforin pokes holes in a membrane | - granzyme B initiates a chain rxn --> leading target cell suicide = apoptosis

Question 36

What occurs when a Killer T cell (CTL) connects its Fas ligand to the Fas protein on the target cell?

Answer 36

Fas protein signaling causes cells to commit suicide

Question 37

What type of death means enzymes and chemicals from the dying cell are released into surrounding tissue and is extremely damaging?

Answer 37

necrosis

Question 38

What type of death means the enzymes and chemicals from the dying cell are neatly contained in vesicles and the vesicles are eaten and disposed of by macrophages?

Answer 38

apoptosis

Question 39

What is the co-receptor for a helper T cell? | What about for a killer T cell?

Answer 39

Helper--> CD4 --> emits cytokines Killer--> CD8 --> kills target cells

Question 40

Describe the difference b/w nairve t cells and experienced t cells.

Answer 40

Naive T cell--> to be activated need two signals: - w/o both signals get anergy - with both signals get activation Experienced/activated T cells--> travel to site of inf. and help/kill and may NOT need secondary signal to do so