T Cell Mediated Immunity- L9

Question 1

Kinetics of a T cell response

Answer 1

Expansion occurs after exposure and number of antigen specific cells is optimal after 1-2 weeks

Question 2

Potential fates of naive T cells

Answer 2

• Effector or memory cells
• Effector cells outnumber the memory cells
• These occur for both CD8 and CD4 naive T cells

Question 3

Cells that prompt T cell activation

Answer 3

Dendritic cells. Take up antigens in skin and move to enter a draining lymphatic vessel. Bear antigen and wait for T cells in lymph node to respond.

Question 4

Processing and presentation of antigen by dendritic cells

Answer 4

• Receptor mediated endocytosis of bacteria
• Macropinocytosis of bacteria or viruses
• Viral infection
• Cross presentation of exogenous viral antigens
• Transfer of viral antigens from infected dendritic cell to resident dendritic cell

Question 5

Proteins controlling migration of naive T cells

Answer 5

• Selectins
• Integrins
• Chemokine receptors
• Control migration in and out of lymph nodes

Question 6

Requirements for activating naive T cells

Answer 6

• Antigen recognition (occurs in lymph node)

- Costimulatory signal (B7/CD28)

Question 7

B7/CD28

Answer 7

Important costimulatory signal for activating naive T cells

Question 8

What if only recognition of antigen occurs?

Answer 8

-Unresponsiveness or anergy

Question 9

What if only costimulation signal occurs?

Answer 9

-Trick question: this has no effect on T cells by itself

Question 10

CD28 ligands

Answer 10

• B7-1 and B7-2
• Expression primarily limited to APCs
• B7-1 (CD80) absent from unstimulated cells
• B7-2 (CD86) is constitutively expressed at low levels on unstimulated dendritic cells and blood monocytes
• B7-2 is the major initial ligand and B7-1 sustains T cell activation

Question 11

CD28 independent responses

Answer 11

• In the presence of a strong first signal, CD-28 mediated co-stimulation is not required
• CD28 costimulation is not required for effector and memory T cells

Question 12

IL-2

Answer 12

Drives proliferation and differentiation of activated naive T cells. Causes the expansion of a specific population of T cells due to autocrine production of IL-2

Question 13

TH1 cells

Answer 13

• Class of CD4 T cell
• IL-2 cytokine
• Activates macrophages

Question 14

TH17 cells

Answer 14

• Class of CD4 T cell

- Enhance neutrophil response

Question 15

TH2 cells

Answer 15

• Class of CD4 T cell

- Activate cellular and antibody response to parasites

Question 16

TFH cells

Answer 16

• Class of CD4 T cell
• Follicular helper cell
• Activate B cell maturation

Question 17

T reg cells

Answer 17

• Class of CD4 T cell

- Suppress other effector T cells

Question 18

CD40 ligand expression

Answer 18

Critical to the ability of CD4+ T cells to activate other cells

Question 19

Lupus

Answer 19

Overexpression of CD40

Question 20

IFN-gamma and IL2 exposure induces

Answer 20

TH1 cells

Question 21

IL4 and IL10 exposure induces

Answer 21

TH2 cells

Question 22

Activation of CD8 T cells

Answer 22

• Makes IL2 to drive its own proliferation and differentiation
• Can also be driven by IL-2 produced by CD4 T cells

Question 23

Granule exocytosis

Answer 23

• CD8 T cells perform it
• Fast killing
• Predominant pathway
• Granzymes (granzyme B cleaves pro-caspases) and perforin (perforin creates holes in membranes)
• Induces apoptosis in target cells through caspase activation and mitochondrial damage

Question 24

Expression of cell surface TNF-family effector molecules

Answer 24

• CD8 T cells
• Slow killing
• Membrane TNF, lymphtoxin, Fas ligand, Trail

Question 25

Secretion of soluble toxic cytokines

Answer 25

• CD8 T cells
• Slow killing
• TNF and interferon-gamma

Question 26

T cell inactivation

Answer 26

• CTLA-4 competes for B7
• Inhibitory receptor for B7
• Binding to B7 leads to anergy
• Also inactivation can be impacted by: Elimination of Ag or other stimuli, T reg cells, or killing by immunoregulatory cells