"Microbiology/Immunology T Cell Immunity" SANA

Question 1

Name the four stages in the kinetics of the T-cell response.

Answer 1

Naive T-cell stage, effector response, clonal stage, decline (homeostasis), memory stage

Question 2

How many days post-infection do memory cells become predominant?

Answer 2

14 days

Question 3

True or false: memory cells outnumber effector cells

Answer 3

false: effector cells outnumber all other cell stages.

Question 4

What is the function of dendritic cells?

Answer 4

take up bacterial antigens in skin and move to draining lymphatic vessel

Question 5

Once a viral infection invades your body, dendritic cells get busy processing antigens to present to T-cells. If the processing is done in nucleated cells, which T-cells will the dendrites present their viral antigens to?

Answer 5

CD8 T-cells which respond to the MHC I antigen presentation. Remember, MHC I is expressed in all nucleated cells.

Question 6

Name the two ways in which pathogenic bacteria is taken up by dendritic cells.

Answer 6

Receptor-mediated endocytosis and macropinocytosis

Question 7

Name 4 ways in which viruses can be taken up by dendritic cells.

Answer 7

Macropinocytosis, viral infection of dendrites, cross-presentation, transfer of viral antigen from one dendrite to another.

Question 8

naive T-cells can enter a draining lymph node by which two routes?

Answer 8

blood vessel or affarent lymph from upstream lymph node

Question 9

What are the two steps required to activate naive T-cells?

Answer 9

Antigen recognition and costimulatory signal

Question 10

The requirement for a cosimulatory molecule in naive T-cell activation is advantageous because:

Answer 10

it is upregulated during innate immune responses, thus making sure that immune system is responding to actual microbes.

Question 11

What is the effect of just antigen recognition between dendritic cells and the T-cells?

Answer 11

No response or anergy, need co-stimulation

Question 12

Expression of cosimulatory molecules is often limited to what type of cells?

Answer 12

Antigen-presenting cells.

Question 13

CD28 is a cosimulatory molecule that attaches to a B7 ligand on an antigen-presenting cell. Name the differences between B7-1 and B7-2 types of ligands.

Answer 13

B7-2 is present constitutively, has faster kinetics and higher expression levels and is responsible for the initial T-cell activation. B7-1 is not present in unstimulated cells and sustains T-cell activation later on.

Question 14

True/False: certain non-naive T-cells can be activated without co-stimulation from CD28

Answer 14

True, these cells will often have alternative pathways.

Question 15

Of the following antigen-presenting cells, which is the only one that can activate naive T-cells?

a. dendritic cells
b. Macrophages
c. B-lymphocytes

Answer 15

a (although activated B-lymphocytes can also activate naive T-cells)

Question 16

Of the following antigen-presenting cells, which is the only one that has constitutive B7 costimulatory activity?

a. dendritic cells
b. Macrophages
c. B-lymphocytes

Answer 16

a

Question 17

Of the following antigen-presenting cells, which two have constitutive MHC class II expression?

a. dendritic cells
b. Macrophages
c. B-lymphocytes

Answer 17

a and c

Question 18

An activated T-cell will express IL-2 receptors of _____ (high/low) affinity.

Answer 18

High

Question 19

proliferation and differentiation of naive T-cells is driven by ______

Answer 19

IL-2

Question 20

activated T-cells secrete _____, which binds to the _____ (high/low) affinity IL-2 receptor and causes _______

Answer 20

IL-2, high, T-cell proliferation.

Question 21

How do T-cells know where to find the site of infection after T-cell activation?

Answer 21

Expression of surface molecule on T-cells changes after activation causing adhesion molecules to be differentially expressed and attracted to specific sites.

Question 22

Which cytokines induce the differentiation of CD4 T-cells into TH1 type cells?

Answer 22

IL2 and IFN-y

Question 23

What is the function of the TH1-type CD4 cell?

Answer 23

To activate macrophages

Question 24

Cytokines IL4 and IL5 are primarily secreted by what class of CD4 T-cells?

Answer 24

TH2

Question 25

What is the function of the TH2-type CD4 cell?

Answer 25

activate cellular and antibody response to parasite.

Question 26

In lupus, which is an autoimmune disease, it is hypothesize that there is an expansion of antibody production due to:

a. overexpression of the CD40 ligand, causing CD4 T-cells to overactivate B-cells
b. defective CD4 T-cells causing no proliferation or differentiation
c. defective processing of viral antigens, causing overactive CD8 T-cells.

Answer 26

a

Question 27

The interaction between a B-cell and a Tcell with specificity for the same antigen is called ________

Answer 27

cognate recognition

Question 28

Name the ligand that helps active CD4+ T-cells activate other cells,

Answer 28

CD40 ligand.

Question 29

Production of IL2 and IFNy causes the expression of the _____ transcription factor leading to CD4 differentiation into_______.

Answer 29

T-bet, TH1 class

Question 30

Your patient has leprosy and you discover that she has a defective TH1 response and dominant TH2 response. What does this mean for your patient? (hint: TH1 response is cell-mediated and can deal with intracellular pathogens).

Answer 30

Because TH1 is the appropriate response and is defective, the disease will be disseminated and have a high bacterial count

Question 31

Which of the following is NOT a function of the TH1 cell?

a. activate macrophages
b. kill chronically infected macrophages
c. induce T-cell proliferations
d. increase TH2 cell proliferation
e. cause macrophage differentiation in bone marrow
f. activate endothelium to induce macrophage adhesion and exit
g. cause macrophages to accumulate at site of infection

Answer 31

d. TH1 cell dont increase TH2 cell proliferation. (But TH2 production of IL-4/IL-13 cytokines can inhibit TH1 function.

Question 32

CD8 cells produce _________

a. cytotoxins
b. immunoglobins
c. endotoxins

Answer 32

a

Question 33

Order the following sequence of events once the naive T-cells (CD8) and antigen-presenting cells interact:

a. proliferation–> cytokine production —> synthesis of cytotoxic effector molecules
b. proliferation –> synthesis of cytotoxic effector molecules–> cytokine production
c. cytokine production –> synthesis of cytotoxic effector molecules–> proliferations

Answer 33

b

Question 34

Give two examples of the CD8 T-cells slow killing mechanisms.

Answer 34

1. expression of TNF family effector molecules on cell-surface
2. secretion of soluble toxic cytokines

Question 35

What is the predominant pathway in the CD8 T-cell killing mechanism?

Answer 35

granule exocytsis: fast killing

Question 36

Arrange the following in the correct sequence of the granule exocytosis molecule:

1. release of perforins and granzymes
2. perforins create holes in target, while granzymes cleaves pro-caspases
3. induce apoptosis by capsase activation and mitochondrial damage
4. reorientation of granules to site of interaction

Answer 36

4, 1, 2, 3

Question 37

T/F? After inducing apoptosis in one cell, the CTL can move and target another cell.

Answer 37

True, CTL kills targets in succession

Question 38

What is CTLA 4 and why is it important in CTL activation?

Answer 38

CTLA-4 is an inhibitory receptor for B7 (costimulatory ligand for T-cells). It competes for binding with CD28 and leads to CTL inactivation.

Question 39

All of the following are factors in ending T-cell response except:

a. deprivation of antigens
b. elimination of Ag
c. T-regulatory signals
d. killing by immunoregulatory cells
e. inhibition by CTLA4
f. feedback inhibition by macrophages

Answer 39

f