T Cell Activation (Exam 3)

Question 1

What chemokine receptor has a role in naive T cell activation via antigen presentation?

Answer 1

CCR7

Question 2

Explain CCR7 receptor’s role in T cell activation.

Answer 2

-on naive T cells and dendritic cells
-bind chemokines which signal cells to move to T cell zone in lymph node (so antigen can be presented)

Question 3

What 3 signals are required to activate naive T cells?

Answer 3

1. MHC-antigen complex
2. APC costimulation
3. Cytokines

Question 4

Why do T cells need costimulation from antigen-presenting cells to be activated?

Answer 4

to prevent overactivation; ensures only they activate them

Question 5

MHC Class I antigens are derived from ________ proteins while MHC Class II antigens are derived from _______ synthesized proteins.

Answer 5

cytosolic
exogenous

Question 6

T cells express ______ which binds to B7 costimulatory molecules on the APC surface, one of the signals required to activate naive T cells.

Answer 6

CD28

Question 7

During costimulation for activation of a T cell, _____ on the T cell binds to ______ on the antigen-presenting cell.

Answer 7

CD28
B7 (costimulatory molecule)

Question 8

What happens when a T cell encounters MHC-antigen complex but with no costimulatory molecules from an APC?

Answer 8

T cell becomes anergic

Question 9

What happens when a T cell encounter MHC-antigen complex in the presence of costimulatory molecules?

Answer 9

drives proliferation + differentiation of T cells with specific effector functions

Question 10

_______ on antigen-presenting cells can enhance their function and therefore, enhance the activation of T cells.

Answer 10

CD40

Question 11

Fill in the blank for the process in T cell activation:

A naive T cell upregulates ______ ligand which binds to ______ on dendritic cell. This leads to expression of ____ and secretion of ______ which stimulates T cell proliferation and differentiation.

Answer 11

CD40
CD40
B7
cytokines

Question 12

Which cells express CD40? Which express CD40L?

Answer 12

CD40: dendritic cells
CD40L: naive T cells

Question 13

What molecule an antagonist of costimulation by competing for B7 on APCs?

Answer 13

CTLA-4

Question 14

To block T cell activation, CTLA-4 competes with ______ on T cells for binding to ______ on APCs.

Answer 14

CD28
B7

Question 15

Term for when an activated T cell recognizes antigen and undergoes proliferation.

Answer 15

clonal expansion

Question 16

Once an infection is eliminated, the majority of the activated effector T cells undergo apoptosis so the immune system returns to __________.

Answer 16

homeostasis

Question 17

List the 3 different T cell subsets that can be polarized.

Answer 17

Th1
Th2
Th17

Question 18

Match which signature cytokines belong to each T cell subset:

1. Th1
2. Th2
3. Th17

Answer 18

1. IFNy
2. IL-4, IL-5, IL-13
3. IL-17, IL-22

Question 19

Th1 cells activate ________ and produce _____ antibodies for what kind of host defense?

Answer 19

macrophages
IgG
intracellular microbes

Question 20

Th2 cells activate what two cell types? Which antibodies do they produce?

Answer 20

mast cells & eosinophils
IgE

Question 21

Th2 cells are involved in host defense against ________.

Answer 21

helminths

Question 22

Th17 cells activate what two cell types? What response does this lead to?

Answer 22

neutrophils + monocytes
inflammation

Question 23

Th17 cells defend the host against what?

Answer 23

extracellular bacteria + fungi

Question 24

What are the 3 steps of polarization of T cell subsets?

Answer 24

1. induction
2. commitment
3. amplification

Question 25

What occurs in the induction stage of polarization of T cell subsets?

Answer 25

innate immune cells produce early cytokines

Question 26

What occurs in the commitment stage of polarization of T cell subsets?

Answer 26

cytokines cause TFs to change gene expression to a specific T helper cell lineage

Question 27

What occurs in the amplification stage of polarization of T cell subsets?

Answer 27

after T cells are activated and polarized, cytokines are produced which can drive other T cells to polarize