CD4 T Cell Effects (Exam 3)

Question 1

What kind of T cell is polarized and activated in response to microbes living in phagosomes of macrophages? What cytokine do they secrete?

Answer 1

Th1 cells
IFN-y

Question 2

In response to a microbe in a phagosome of a macrophage, Th1 cells secrete IFN-y which has what effect?

Answer 2

activates macrophage to kill microbe

Question 3

(T/F) Th1 cells directly kill microbes in phagosomes of macrophages by secreting IFN-y.

Answer 3

False - activate macrophage which directly kills it

Question 4

Th1 cells are stimulated to respond to microbes in phagosomes of macrophages when APCs secrete what cytokine?

Answer 4

IL-12

Question 5

What cells respond to microbes NOT in phagosomes, but are the cytoplasm of infected cells? How do they respond?

Answer 5

CTLs (CD8+ cytotoxic T cells)
direct killing of infected cell

Question 6

What are the 3 phases of the cell-mediated immune response (T cells)?

Answer 6

1. induction phase
2. migration phase
3. effector phase

Question 7

In the induction phase of cell-mediated immunity, _____ present antigen to T cells which leads to their proliferation and differentiation. These cells enter ________.

Answer 7

APCs
circulation

Question 8

During the migration phase of cell-mediated immunity, circulating T cells bind to activated _________ on endothelial cells which bring them to the infection site.

Answer 8

adhesion molecules

Question 9

During the effector phase of cell-mediated immunity, T cells recognize specific antigen and secrete _______ which causes what response?

Answer 9

cytokines
activate phagocytes + inflammation

Question 10

What happens to T cells which are not specific for antigen that arrive at the infection site?

Answer 10

return to circulation

Question 11

List 2 functions of Th1.

Answer 11

1. classical macrophage activation
2. bind complement / opsonization of IgG

Question 12

List 5 functions of Th2.

Answer 12

1. produce IgE
2. repair tissues
3. mast cell degranulation
4. barrier immunity (GI)
5. activate eosinophils

Question 13

In terms of Th2 and its function in GI barrier immunity, what two specific things does it do?

Answer 13

mucous secretion
peristalsis

Question 14

Th2 functions in tissue repair via _______ macrophage activation which causes ________ and ________.

Answer 14

alternative
collagen synthesis
fibrosis

Question 15

List 3 functions of Th17.

Answer 15

1. activate neutrophils/inflammation
2. secrete antimicrobial peptides
3. increase mucosal barrier

Question 16

What is the role of IL-12 in cell-mediated immunity? Which T helper cell develops?

Answer 16

APCs secrete IL-12 which stimulates Th1 development

Question 17

What happens to T cells that recognize their specific antigen at the infection site?

Answer 17

retained at site to stimulate inflammation & killing of microbes

Question 18

What happens to T cells which are not specific for antigen that arrive at the infection site?

Answer 18

return to circulation via lymphatic vessels

Question 19

What is the role of CD40-CD40L?

Answer 19

binding –> stimulate APC to secrete IL-12 = differentiation of Th1

Question 20

What is the role of IFN-y? What is it produced by?

Answer 20

activates macrophages to kill phagocytized microbes

produced by Th1 cells

Question 21

When macrophages become activated, they produce _______ and _______ which kill the microbes in their phagosomes.

Answer 21

nitric oxide
lysozyme

Question 22

_____ cells facilitate tissue repair by secreting ____ and ____, activating macrophages to express enzymes which promote collagen synthesis and fibrosis.

Answer 22

Th2
IL-4 + IL-13

Question 23

What happens when activated macrophages cannot eradicate an infection?

Answer 23

continued cytokine and GF production –> tissue injury –> fibrosis

Question 24

What is the hallmark of chronic delayed type of hypersensitivity reactions or DTH?

Answer 24

fibrosis

Question 25

When macrophages cannot eradicate an infection, chronic cytokine signals cause macrophages to take on appearance of ______ cells and fuse to make ________ cells.

Answer 25

skin epithelial cells
multinucleated giant cells

Question 26

Term for nodules of inflammatory tissue created by chronically activated macrophage clusters when an infection cannot be eradicated.

Answer 26

granulomas

Question 27

What immune response is predominant in helminth infections?

Answer 27

Th2 effector T cell response

Question 28

Of the Th2 effector T cell response to helminth infection, ___ and ___ cytokines produce IgE and ____ activates eosinophils which bind to the worm to release granules and destroy its integument.

Answer 28

IL-4 + IL-13
IL-5

Question 29

What are 2 types of memory T cells?

Answer 29

central memory T cells
effector memory T cells

Question 30

Where do central memory T cells go? Effector memory T cells?

Answer 30

central: lymph nodes
effector: peripheral tissues

Question 31

Match each to the appropriate memory T cell type:

1. immediate vs. limited effector functions
2. rapid proliferation vs. no proliferation

Answer 31

Central: limited effector function, rapid proliferation

Effector: immediate effector function, no proliferation