BIIC Immunology Lecture 2_Cell Mediated Adaptive Immunity Part 1

Question 1

Can TCRs be activated by free antigens?

Answer 1

No TCRs can only be activated by MHC bound antigens. The one exception to this is gamma delta T cells which are rare

Question 2

What are the 4 stages of T cell development and what is unique about each stage?

Answer 2

1) Pro T Cell: Recombination of the Beta Chain
2) Pre T Cell: Recombination of the alpha chain
3) Immature T Cell: Double Possitive for CD4 and CD8
4) Mature T Cell: Single Positive for either CD4 or CD8

Question 3

What is the role of CD4 and CD8 at the Immunologic Synapse?

Answer 3

They bind MHC and hold it inplace on the TCR

Question 4

What is the role of CD 3 at the Immunologic Synapse?

Answer 4

It sits close to the TCR and propigates signal transduction When the TCR is bound to MHC.

Question 5

What does CD28 band and what does it do?

Answer 5

CD28 binds B7 and co stimulates the T Cell response

Question 6

What does CTLA-4 bind and what does it do?

Answer 6

It binds B7 and inhibits further T cell response (it turns it off)

Question 7

How do some bacteria take advantage of the immunologic synapse?

Answer 7

Intracellular bacteria can pass from the infected cell to the T cell through the synapse

Question 8

What two activations are required for T cell activation

Answer 8

TCR has to bind MHC and CD28 has to bind B7

Question 9

What is the end result of T cell activation?

Answer 9

production of three transcription factors:

1. NFAT
2. NF-kB
3. AP-1

Question 10

The three transcription factors of T cell activation cause the T Cell to produce what? What does it do

Answer 10

IL 2 is created. The IL-2 cna then have an autocrine effect on the T Cell and complete activation

Question 11

What does IL-2 do to activate T Cells?

Answer 11

it binds to IL-2R and stimulates clonal proliferation by activating JAK/STAT

Question 12

What is the MOA of the drugs Cyclsporin and Tacrolimus?

Answer 12

They suppress the transcription factor NFAT which then prevents IL-2 production and suppress T cell activation. Theses drugs are given to people with autoimmune diseases

Question 13

How is T cell activation terminated?

Answer 13

After several rounds of proliferation CTLA-4 binds to B7 and this stops the T cell

Question 14

What are the 3 types of effector T cells and what do they fight?

Answer 14

▪ For TH1: Many bacteria, viruses, & fungi (more
intracellular pathogens). Role in chronic inflammation
▪ For TH2: Parasites and allergens (more extracellular
pathogens)
▪ For TH17: Extracellular pathogens and a role in
autoimmune disorders

Question 15

Which Cytokines drive the differentiation of effector T cells?

Answer 15

▪ IL-12 and IFN-g→TH1
▪ IL-4 →TH2
▪ IL-6 and TGF-β→TH17