T Cell Immunity

Question 1

What are the two types of T cell receptors?

Answer 1

• alpha-beta
• gamma-delta
• T-cell will have one or the other, not both

Question 2

What is the most common type of T cell receptor?

Answer 2

-alpha-beta

Question 3

What are CD4 and CD8 with respect to T cell receptors?

Answer 3

-co-receptors

Question 4

What do alpha-beta receptors recognize?

Answer 4

BOTH the presented peptide and the MHC molecule

Question 5

How do T-cell receptors signal the T cell nucleus?

Answer 5

• CD3 complex
• TCRs cluster together
• CD3 recruits kinase enzymes to activate nucleus & proliferation

Question 6

What do CD8 and 4 do?

Answer 6

clip onto either MHC I (CD8) or MHC II (CD4)

=focus the attention of Th and CTL cells on the proper MHC molecule, stabilizes connection

-strengthen TCR signal to the nucleus

Question 7

What acts as the costimulatory signal to activate naive T cells?

Answer 7

-B7

**on B cells and dendritic cells

Question 8

What happens when CD40L on the Th cell binds to the CD40 receptor on the dendritic cell?

Answer 8

• dendritic expression of MHC and B7 will be increased

- dendritic cell’s lifespan is also extended

Question 9

What do helper T cells do once they are activated?

Answer 9

• parts ways with APC
• proliferate
• produce large amounts of IL-2

Question 10

What is a brief sequence of T cell activation?

Answer 10

• Adhesion molecules mediate weak binding between Th and APC
• TCR’s engage their cognate antigen presented by APC
• Receptor engagement strengthens the adhesion
• Upregulates CD40L expression on the Th cell
• CD40L binds to CD40 on the APC
• Stimulates expression of MHC and co-stimulatory molecules on APC
• When activation is complete the Th cell proliferates
• This proliferation produces clones of helper T cells which recognize the invader

Question 11

How do helper T cells enhance the action of Cytotoxic T Lymphocytes?

Answer 11

• Help CTLs kill efficiently
• Th also help CTL’s become long-lived
• helps CTL’s generate memory T cells
• Provide IL-2 needed for CTL’s to proliferate (controls strength of response)

Question 12

What interleukin is produced by activated dendritic cells once they reach a lymph node?

Answer 12

IL-12

Question 13

What does IL-2 from T helper cells do?

Answer 13

• recharges natural killer cells

- stimulates growth of Cytotoxic T lymphocytes, NK cells, and Th1 cells

Question 14

What do Th1 cytokines do?

Answer 14

• instruct the innate and adaptive systems to produces cells and antibodies against both viruses and bacteria
• IFN-gamma tells B cells to switch to IgG3

Question 15

Which cytokines are produced by Th2 cells?

Answer 15

• IL-4
• IL-5
• IL-13

Question 16

What does IL-4 do?

Answer 16

• stimulates production of Th cells
• stimulates B cell growth
• Influences production of IgE antibodies (good against parasites)

Question 17

What does IL-5 do?

Answer 17

• encourages B cells to produce IgA

* useful in protecting GI tract

Question 18

What does IL-13 do?

Answer 18

• stimulates production of mucus in GI system

* protects against pathogen invasion

Question 19

What do Th0 cells do?

Answer 19

-remain “unbiased” when first activated, retaining the ability to produce a wide range of cytokines

Question 20

Do cytokines act locally or systemically?

Answer 20

Locally

Question 21

What produces perforin and what does it do?

Answer 21

• produced by cytotoxic T cells

- binds to cell membranes and drills holes in them

Question 22

What does a cytotoxic T cell use to kill its foes?

Answer 22

• perforin
• Granzyme B (triggers Apoptosis)
• FasL (binds Fas, triggers Apoptosis)

Question 23

What cytokines are produced by Th1 cells?

Answer 23

• TNF
• IFN-gamma
• IL-2

Question 24

What do Th17 cells do?

Answer 24

Fight fungus