Immunology

Question 1

Describe the innate response to malarial infection.

Answer 1

PAMPs: DPI bridges, haemozoin, and parasitic specific nucleic acids are detected, via Complement in blood, Toll-like receptors on and in cells.
This cause the release of cytokines such as IL-1, IL-6, and TNF. This leads to inflammation.
Inflammation:
Pain
Pyrexia- to reduce the growth and development of pathogens
Increase vascular permeability- Leaky to allow more lymphocytes to enter tissues
In malaria:
A huge amount of cytokines overwhelms the immune system
An increase in vasodilation and leakiness leads to hypotension
leads to coagulation
Systemic Organ failure.

Question 2

What are the T-Cell responses in malarial infection?

Answer 2

Th1- IFN-y stimulates the Cytotoxic T Cells CD8, and kills via Perforins and granzymes. Also activates Macrophage and DC to phagocytose. Hepatic stage
Th2- IL-4 stimulates B Cell Activation and starts producing Ab.
Follicular T cell aids Follicular B cells
Th17 activates neutrophils

Question 3

What type of immune response is required for malarial infection?

Answer 3

Sterilising immunity

Question 4

Explain how transmission-blocking vaccines work

Answer 4

When the mosquito feeds, the antibodies are taken up by the
mosquito and these can block the parasite from proliferating in the
mosquito
* This results in “herd immunity”
First-person has to be infected

Question 5

Describe the differences in intravascular and extravascular haemolysis.

Answer 5

I- Breakdown in vessels, this leads to free Hb in blood which is toxic to the kidneys.
E-

Question 5

Describe the differences in intravascular and extravascular haemolysis.

Answer 5

I- Breakdown in vessels, leads to free Hb in the blood which is toxic to the kidneys.
E- Breakdown in spleen via splenic macrophages, bilirubin in kidneys, bile in GIT.

Question 6

In CAIHA, what are the two Ag systems that are involved?

Answer 6

P- for IgG (Donath lanelstein)
I- IgM

Question 7

Explain how IgG-coated cells are destroyed.

Answer 7

Opsonizing of cells for phagocytosis
detected by FcR
pseudopodia forms and engulfs cells
forms a phagosome in which cells are destroyed

Question 8

Explain how IgM-coated cells are destroyed.

Answer 8

Complement mediated lysis
Ig-M binds to the cell membrane
activates circulating complement proteins
produces a cascade of reactions (complement proteins activated)
forming the membrane attack complex MAC
Produces pores- the influx of water and ions that cause the cell to burst

Question 9

How do Natural killer cells kill Ab-coated cells?

Answer 9

Antibody-Dependent Cellular Cytotoxicity
Recognizes Ab coated via FcR
Once bonded to the antibody activates the NK cell
Releases perforins that create pores in cells and then release granzymes that enter the cell
Activates Caspases which induces apoptosis
Also kills via TNF-a