T-lymphocyte Practice

Question 1

All CD8+ T cells (cytotoxic T cells) are ? restricted

Answer 1

Class I MHC-restricted (HLA-1)

Question 2

All CD4+ T cells (helper T cells) are ? restricted

Answer 2

Class II MHC-restricted (HLA-2)

Question 3

MHC Class I molecules are present on all nucleated cells and present ?

Answer 3

endogenous peptides

Question 4

MHC Class II molecules present ?

Answer 4

exogenous peptides

Question 5

What are the 3 interactions needed for a Naive T cell to be activated from APC?

Answer 5

• T-cell receptor interaction with HLA-2
• CD4 co-receptor interacting with HLA-2
• Co-stimulatory interaction: CD28 interaction with CD80/86

Question 6

What is the major costimulator on the APC?

Answer 6

CD80/86

Question 7

what does the CD80/86 on the APC bind to?

Answer 7

CD28 on the Th

Question 8

What is a major T cell and B cell growth factor?

Answer 8

IL-2

Question 9

Once the naive T cell is activated, it begins to synthesize ? and ?

Answer 9

IL-2 and the high-affinity form of the IL-2 receptor

Question 10

IL-2 binding to the Th IL-2R acts in an ?

Answer 10

autocrine fashion

Question 11

What happens when the IL-2 bind to the Th IL-2R?

Answer 11

activates the Th cell and causes it to enter the cell cycle, as well as avoid apoptosis

Question 12

What does IL-2 do to help Th cells to avoid apoptosis?

Answer 12

upregulates Bcl-2 - an apoptosis inhibitor

Question 13

synthesis of both IL-2 and the high-affinity IL-2R is induced after what?

Answer 13

CD28-CD80/86 binding and recognition of antigen by the TCR (via HLA-2)

Question 14

Ag recognition in absence of co-stimulation causes what?

Answer 14

T cell anergy

Question 15

Anergic T cells can or cannot produce IL-2?

Answer 15

CANNOT

Question 16

How do helper T-cells aid immunity?

Answer 16

• activate or inhibit other cells through direct contact
• activate or inhibit other cells through secretion of cytokines

Question 17

Th cells will differentiate after they are activated so that they “help” in a specific way - this is known as ?

Answer 17

T-cell polarization

Question 18

What is specialization of Th phenotype called?

Answer 18

polarization

Question 19

What determines what the Th type will be?

Answer 19

the environment it is found in, in particular the TYPES of CYTOKINES that are present in high concentrations in the immediate vicinity of the newly activated Th

Question 20

What are the cytokines called that influence an activated Th type to be?

Answer 20

polarizing cytokines

Question 21

What secretes the polarizing cytokines which influence the Th type to be?

Answer 21

APC usually dendritic cells

Question 22

What is the principal effector actions of Th1 cells?

Answer 22

macrophage activation

Question 23

What are the major Th1 polarizing cytokines?

Answer 23

IL-12, IL18

Question 24

What happens when IL-12 and IL-18 bind to the receptors on the Th cell?

Answer 24

activation/production of the Th1 transcription factor

Question 25

what is the Th1 transcriptions factor?

Answer 25

Tbet

Question 26

What are the effector cytokines that Th1 cells secrete?

Answer 26

IFN-y and TNF

Question 27

Macrophages require 2 signals for activation which are:

Answer 27

- IFN-y - Cell contact: CD40-CD40L

Question 28

Th cells usually first activated and polarized in where?

Answer 28

secondary lymphatic tissue/organs

Question 29

Signals generated by a polarized Th cell tend to prevent other local Th cells from being polarized into a different type, this is known as ?

Answer 29

cross-regulation

Question 30

What are the 3 major polarizing cytokines for Th17?

Answer 30

IL-6, IL-23, TGF-b

Question 31

What are the effector cytokines that Th17 produces?

Answer 31

IL-22 and IL-17

Question 32

What does IL-22 and IL-17 do? (effector cytokines of Th17)

Answer 32

- induce release of IL-16, IL-1, TNF-a, GM-CSF - cause release of chemokines that recruit neutrophils and macrophages - cause secretion of anti-microbial proteins from cells in inflamed tissue

Question 33

What is the transcription factor of Th17?

Answer 33

ROR-yt

Question 34

What is common between Th1 and Th17 cells?

Answer 34

both cause activation of macrophages and increased phagocytosis

Question 35

What is the major polarizing cytokine for Th2 cells?

Answer 35

IL-4

Question 36

What is the determining transcription factor for Th2 cells?

Answer 36

GATA-3

Question 37

What are the Th2 effector functions?

Answer 37

- production of IgE and IgA - secretion of IL-4, IL-5, IL-13

Question 38

What do Th2 cells recruit that are specialized to fight parasitic infections?

Answer 38

eosinophils

Question 39

Th2 cells are also implicated as major causative factors in what?

Answer 39

allergic disease

Question 40

What is unique about Tfh (follicular Th cells)?

Answer 40

they typically stay in the SLO and aids full B-cell development

Question 41

We make "2 rounds" of antibodies when we experience an infection that our immune system has trouble clearing, these 2 rounds are:

Answer 41

Round 1 - lower-affinity antibodies, many epitopes Round 2 - B cells "reshuffle" their antibodies and the ones that are very high affinity are selected to reproduce in germinal centres

Question 42

What is the "2 rounds" of B-cell antibody production known as?

Answer 42

affinity maturation

Question 43

What are the 2 major steps to TFH polarization

Answer 43

1. Naive Th interacts with dendritic cells in SLOs and become a Tfh effector cell 2. Tfh migrates to the B-cell region of the SLO and interacts with B-cells that present antigen via their HLA-2

Question 44

What is inhibitory to Tfh development?

Answer 44

IL-2

Question 45

What is the polarizing cytokine for Tfh in humans?

Answer 45

IL-12

Question 46

What is the transcription factor for Tfh

Answer 46

Bcl6

Question 47

the new Tfh expresses a ? that allows it to migrate to the B-cell zone of an SLO and it is called ?

Answer 47

chemokine CXC5

Question 48

Tfh interacts with a B-cell via TCR-HLA2 and two other new costimulator interactions:

Answer 48

- iCOSL on B-cells interacts with iCOS on Tfh - CD40L on Tfh interacts with CD40 on B-cells

Question 49

interaction between iCOSL and iCOS stimulates what?

Answer 49

cytokine production by the Tfh

Question 50

interaction between CD40L and CD40 stimulates what?

Answer 50

stimulates the B-cell to increase antibody production

Question 51

What is the major Tfh effector cytokine?

Answer 51

IL-21

Question 52

IL-21 and CD40-CD40L are key for what?

Answer 52

key for full B-cell maturation and development of the germinal centres where most antibodies are produced

Question 53

The development of regulatory T-cells is unique in that their effector activities ?effector activities of other immune cells

Answer 53

down-regulate

Question 54

Treg arise in environments where APCs present an antigen in a cytokine environment that is predominantly what?

Answer 54

"anti-inflammatory"

Question 55

What is the inducing/polarizing cytokine for Treg?

Answer 55

TGF-B

Question 56

animals or humans that cannot produce effective Tregs usually develop what?

Answer 56

severe autoimmune disease

Question 57

what is the transcription factor that causes a Th to become a Treg?

Answer 57

FoxP3

Question 58

What are the effector functions of the Treg

Answer 58

- secretion of anti-inflammatory cytokines: TGF-B, IL-10 - down-regulation of CD80/86 signaling by binding to Treg CTLA-4 - soaking up and "stealing" IL-2 from other effector T-cells

Question 59

cytokines from one Th type can prevent the proliferation or survival of other Th types, this process is known as ?

Answer 59

cross-regulation

Question 60

Cytotoxic T-cells kill cells that express abnormal intracellular antigens on ?

Answer 60

HLA-1

Question 61

Cytotoxic T-cells are activated by?

Answer 61

Th1 cells

Question 62

Once a CD8+ T cell has differentiated into an armed effector cell, encounter with its specific Ag results in immune attack without the need for ?

Answer 62

co-stimulation