Exam 2: Dr. Pinchuk T-cell Mediated Immunity 1

Question 1

What are the 3 signals to activate naive T cells?

Answer 1

1) Antigen-specific signal
2) Co-stimulatory signal
3) Cytokine signal

Question 2

When do naive T cells encounter antigen?

Answer 2

During their recirculation through secondary lymphoid organs

Question 3

Describe how naive T cells encounter their antigen

Answer 3

T cell enter a lymph node across high endothelial venues in the cortex
T cells monitor antigen presented by macrophages and DCs
T cells which do not encounter specific antigen leave the node in the efferent lymph
T cells that encounter specific antigen proliferate and differentiate to effector cells

Question 4

What are the broad roles of cell adhesion molecules in the generation of immune response?

Answer 4

Migration of the naive T cells through the lymph nodes
Initial interactions with APC
Migration of the effector T cells into the peripheral tissues
Interactions with target cells

Question 5

What are adhesion molecules doing?

Answer 5

Initiating and controlling T cell contacts with APC

Question 6

What is the affinity like with adhesion?

Answer 6

First adhesion is low affinity and then it becomes his affinity to increase contact time

Question 7

What is the first signal?

Answer 7

Specific, T cell receptors and MHC-antigen interactions

Question 8

What does the first part of TCR complex do?

Answer 8

Recognize antigen

Question 9

What does CD3 complex do?

Answer 9

Signals

Question 10

What does TCR complex plus CD3 do?

Answer 10

Provides antigen recognition plus signaling

Question 11

What deliver a signal 1?

Answer 11

Binding of the TCR and its co-receptor(s) CD4/CD8 to the peptide:MHC class II/MHC class I complex(es) on the DC

Question 12

What delivers signal 2?

Answer 12

Binding of the T cell CD28 to B7 expressed on DC

Question 13

What does T tolerance to antigens expressed on non-professional APC result from?

Answer 13

Antigen recognition in the absence of the co-stimulatory signal

Question 14

What is CD80? CD86?

Answer 14

B7-1

B7-2

Question 15

What is the co-stimulatory signal very important for?

Answer 15

Proliferation

Question 16

What is signal 2 known as? Why?

Answer 16

Survival signal

Without it, T cells will die

Question 17

What does the second signal need to work?

Answer 17

Specific signal

Question 18

What causes the initiation of signal transduction?

Answer 18

Clustering of the TCR and accessory molecules together on the cell surface
Phosphorylation of cytoplasmic portion of the CD3 and z chains
Activation of adaptor proteins and biochemical intermediates
Concentration of intracellular signaling molecules around the receptors

Question 19

What causes the transmission and amplification of the signal?

Answer 19

Activation of certain intracellular enzymes

Question 20

What causes the transmission of the signal to the nucleus?

Answer 20

Transcriptional activation of genes that are silent in resting T lymphocytes

Question 21

Look at signaling through TCR chart

Answer 21

Look at signaling through TCR chart

Question 22

What do activated T cells do?

Answer 22

Secrete and respond to interleukin-2

Question 23

What does rapamycin target?

Answer 23

IL-2 receptor and secretion

Question 24

What do resting T cells express?

Answer 24

A moderate affinity IL-2 receptor

Question 25

What do activated T cells express?

Answer 25

A high affinity IL-2 receptor and secrete IL-2

Question 26

What does the binding of IL-2 to its receptor do?

Answer 26

Signals the T cell to enter the cell cycle

Question 27

Do effector T cells depend on co-stimulatory signals?

Answer 27

No

Question 28

What helps in the activation of Th1 cells?

Answer 28

IL-12 | IFN-γ

Question 29

What does IL-12 and IFN-γ produce from Th1 cells?

Answer 29

IL-2 IFN-γ TNF-α TNF-β

Question 30

What is the major target cell for Th1?

Answer 30

Macrophages

Question 31

What helps in the activation of Th2 cells?

Answer 31

IL-4

Question 32

What does IL-4 produce from Th2 cells?

Answer 32

IL-4 and IL-5

Question 33

What does IL-4 do?

Answer 33

Direct Th2 differentiation

Question 34

What are Th2 cells involved in?

Answer 34

Immunity to helminths

Question 35

What helps in the activation of Tfh cells?

Answer 35

IL-6

Question 36

What does Tfh work with?

Answer 36

Germinal centers

Question 37

What does IL-6 release in Tfh cells?

Answer 37

IL-17

Question 38

What helps with the activation of Th17 cells?

Answer 38

IL-6 and TGF-β

Question 39

What are Tregs in the presence of?

Answer 39

TGF-β

Question 40

What do Th1 cells activate?

Answer 40

Infected macrophages

Question 41

What are the signals that Th1 cells send to macrophages?

Answer 41

CD40 and IFN-γ

Question 42

When do granulomas form?

Answer 42

When T cells cannot activated or only partially activated the macrophage

Question 43

What happens in Th1 complete macrophage activation?

Answer 43

Th1 cell and infected macrophage come together T cell binds to and activates macrophage Killing of intravesicular bacteria

Question 44

What happens in Th1 partial macrophage activation?

Answer 44

Partial activation of macrophage leads to granuloma formation

Question 45

What does IFN-γ do?

Answer 45

Proliferation and differentiation Macrophage activation Complement binding and opsonizing antibodies Opsonization and phagocytosis

Question 46

What does Fas Ligand or TNF-β from Th1 cells do?

Answer 46

Kills chronically infected cells releasing bacteria to be destroyed by fresh macrophages

Question 47

What does IL-2 from Th1 cells do?

Answer 47

Induces T cell proliferation | Increasing numbers of effector cells

Question 48

What does TNF-α and TNF-β from Th1 cells do?

Answer 48

activates endothelium to induce macrophage binding and exit from blood vessel at site of infection

Question 49

What do Th2 cells simulate?

Answer 49

The proliferation and differentiation of naive B cells

Question 50

What occurs with B cells in the presence of IL-4?

Answer 50

Somatic hypermutation and class switching

Question 51

What are T follicular helper cells?

Answer 51

CD4+ T cells that enter the germinal center to mediate their helper function for antibody production

Question 52

What are BCR roles in B cell activation?

Answer 52

Signals to the B cell's interior when antigen is bound | Delivers `the bound antigen to intracellular sites

Question 53

What is linked recognition?

Answer 53

Specific activation of the B cell by its cognate T cell

Question 54

Do T cells and B cells recognize identical epitopes on the same protein?

Answer 54

No

Question 55

What should the peptide recognized by the T cell be physically associated with? Why?

Answer 55

The antigen recognized by the B cell, so that the B cell after internalization of the antigen will produce an appropriate peptide

Question 56

Why is the requirement of linked recognition important?

Answer 56

Self tolerance

Question 57

When will autoimmune responses occur?

Answer 57

Only if both a self-reactive T cell and B cell are present at the same time

Question 58

What is the "bystander effect"?

Answer 58

Activation of lymphocytes that are not specific for the antigens of the infectious agent

Question 59

What happens if activation of the B cell by a Th2 cell is not primed by the same antigen?

Answer 59

It is followed by the availability of the self-antigen, pro-inflammatory cytokines, and IL-1 and IL-6 inhibit Tregs

Question 60

What B cells can helper T cells recognize?

Answer 60

Those that have the same antigen

Question 61

What are the functions of IL-17?

Answer 61

``` Neutrophil accumulation Monocyte accumulation Increased mucin secretion Synergy with IL-1β, IL-6, TNF-α, and GM-CSF Augmentation of inflammation ```

Question 62

What are cellular and humoral adaptive immune response initiated and controlled by?

Answer 62

Effector T cells- CD4 Th and CD8 cytotoxic cells

Question 63

Which APC is the most efficient at activating naive T cells?

Answer 63

DCs

Question 64

What do CD4 T cells play a central role in?

Answer 64

The function of the immune system

Question 65

What do CD4 T cells help B cells make?

Answer 65

Antibody

Question 66

What do CD4 T cells do?

Answer 66

Induction and control of Ig class switching and somatic hypermutation Enhance priming and maintain response of CD8 T cells Regulate macrophage function Enhance neutrophil response Orchestrate immune response against a wide variety of pathogenic microorganisms Regulate immune response to adjust their magnitude and persistence Suppress immune responses to control autoimmunity

Question 67

What are CD4 T cells important mediators involve?

Answer 67

Immunologic memory

Question 68

What happens without CD4 T cells?

Answer 68

Patients have SCID