Immunology II

Question 1

Where are CD28 and B7 located on?

Answer 1

CD28 is found on T cells. B7 is found on APC, such as activated macrophages.

Question 2

What are the adhesion molecules involved in interaction of activated CD8 T cells with infected molecules?

Answer 2

LFA-1 on T cell interacts with ICAM on target cell.

Question 3

What are the 3 proteins found in lytic granules released by cytotoxic T cells? State their function.

Answer 3

Perforin - Polymerises to form a pore in the bacterial cell membrane
Granzymes - Serine proteases which will activate apoptosis once inside the cytoplasm of the target cell
Granulysin - Induces apoptosis

Question 4

What other 4 substances are released from activated cytotoxic T cells?

Answer 4

1. IL-2: further stimulates the differentiation and proliferation of more CD8 T cells
2. IFN gamma: blocks viral replication which will lead to viral death without cell death
3. TNF alpha: activates and induces NO production
4. TNF beta: activates macrophages, directly cytotoxic

Question 5

What are the 3 molecules/cells activated by CD4 Helper T cells and what are they activated to do?

Answer 5

1. CD8 T cell: kill virally infected cells (through release of IFN gamma)
2. Activates macrophages to kill intracellular bacteria
3. Activates B cells to activate neutrophils to remove extracellular bacteria and fungi

Question 6

What are the actions of Th1, Th2 and Th17?

Answer 6

Th1: CMI. activates macrophages, targets intracellular infections. helps B cells in antibody production
Th2: Humoral. activates B cells, mast cells, eosinophils, targets extracellular parasites and also helps B cells in antibody production.
Th17: Amplify inflammation and attracts neutrophils to clear extracellular bacteria and fungi

Question 7

Which is formed in the presence of infection, and which is formed in the absence of infection? Treg, Th17

Answer 7

Treg is formed in the absence of infection whereas Th17 is formed in the presence of infection.

Question 8

What is targeted by macrophages? Is it extracellular or intracellular?

Answer 8

Macrophages remove intracellular pathogens.

Question 9

What is targeted in B cell activation?

Answer 9

B cells kill extracellular bacteria and fungi (pathogens)

Question 10

MHC I contains alpha or beta chain genes?

Answer 10

Alpha.

Question 11

MHC II contains alpha or beta chain genes

Answer 11

Both alpha and beta gene

Question 12

In direct or indirect allorecognition was non-self MHC involved?

Answer 12

Direct allorecognition.

Question 13

Which (direct or indirect allorecognition) will there be fewer T cells activated?

Answer 13

Indirect allorecognition

Question 14

Describe graft-versus-host-disease. How is it different from normal solid organ transplant rejection?

Answer 14

In GVHD, the donor organ (usually a bone marrow), will perceive the recipient tissues as foreign and rejects it. However, in solid organ transplant rejection, the recipient rejects the transplanted organ/graft.

Question 15

Hyperacute rejection occurs mainly from?

Answer 15

Blood group mismatches

Question 16

What is the difference between hyperacute and acute rejection?

Answer 16

Hyperacute rejection occurs immediately when the graft is first inserted.
In acute rejection, the graft is accepted for the first 10 - 13 days, and is then rejected.

Question 17

What type of rejection occurs in acute rejection as opposed to chronic rejection?

Answer 17

In acute rejection, there is direct cytotoxic effect after the first 10 - 13 days.
In chronic rejection, the progress is slow, with gradual laying down of fibrous tissue.

Question 18

Which phagocyte is responsible for eliminating IgE coated parasites such as helminths?

Answer 18

Eosinophils

Question 19

Are neutrophils seen in the blood stream in healthy individuals?

Answer 19

Yes. But in infected individuals, neutrophils will be seen in the infected tissues.

Question 20

Do leukocytes adhere to the walls of arteries?

Answer 20

No, only adheres to and rolls along the walls of veins.

Question 21

Where are naive T and B cells activated?

Answer 21

In peripheral lymphoid organs, such as lymph nodes, spleen, GALT, BALT, and MALT (Gut, Bronchial, Mucosal-associated lymphoid tissues).

Question 22

CD40 ligand is on T cells or B cells? When is CD40 ligand and CD40 interaction involved?

Answer 22

CD40 ligand is on T cells. CD40 is on B cells.

CD40 ligand-CD40 interaction occurs in isotope class-switching of B cells.