"Microbiology/Immunology T Cell Immunity" SANA Flashcards

1
Q

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

A

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

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2
Q

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

A

14 days

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3
Q

True or false: memory cells outnumber effector cells

A

false: effector cells outnumber all other cell stages.

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4
Q

What is the function of dendritic cells?

A

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

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5
Q

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?

A

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

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6
Q

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

A

Receptor-mediated endocytosis and macropinocytosis

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7
Q

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

A

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

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8
Q

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

A

blood vessel or affarent lymph from upstream lymph node

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9
Q

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

A

Antigen recognition and costimulatory signal

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10
Q

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

A

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

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11
Q

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

A

No response or anergy, need co-stimulation

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12
Q

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

A

Antigen-presenting cells.

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13
Q

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.

A

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.

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14
Q

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

A

True, these cells will often have alternative pathways.

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15
Q

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

A

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

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16
Q

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

A

a

17
Q

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

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

A

a and c

18
Q

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

A

High

19
Q

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

A

IL-2

20
Q

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

A

IL-2, high, T-cell proliferation.

21
Q

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

A

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

22
Q

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

A

IL2 and IFN-y

23
Q

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

A

To activate macrophages

24
Q

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

A

TH2

25
Q

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

A

activate cellular and antibody response to parasite.

26
Q

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.

A

a

27
Q

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

A

cognate recognition

28
Q

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

A

CD40 ligand.

29
Q

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

A

T-bet, TH1 class

30
Q

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).

A

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

31
Q

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

A

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

32
Q

CD8 cells produce _________

a. cytotoxins
b. immunoglobins
c. endotoxins

A

a

33
Q

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

A

b

34
Q

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

A
  1. expression of TNF family effector molecules on cell-surface
  2. secretion of soluble toxic cytokines
35
Q

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

A

granule exocytsis: fast killing

36
Q

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
A

4, 1, 2, 3

37
Q

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

A

True, CTL kills targets in succession

38
Q

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

A

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

39
Q

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

A

f