Lecture 8.2: Immunopathology 1

Question 1

True or false? Hypersensitivity Type 1,2,3 involve antibodies such as IgE, Type 4 involves CD4.

Answer 1

True

Question 2

What are the signs of hypersensitivity type 1?

Answer 2

High levels of IgE. Higher in more serious cases such as anaphylactic shocks.

Large numbers of IL-4 secreting Th2 cells -> sensitisation phase.

Question 3

What is sensitisation?

Answer 3

Low dose antigen promotion of Th2 via production of IL-4 by eosinophils. Th2 promotes isotype switching, and is possible due to microenvironment consisting of IL-4,5,13 that changes IgM to IgE.

Question 4

True or false? DC’s produce IL-4 as part of the sensitisation phase.

Answer 4

False. They produce IL-33, inducing basophils to produce IL-4. Basophils can themselves act as APCs.

Question 5

Mast cell activation leads to what 3 things?

Answer 5

Secretion of preformed mediators: histamine, tryptase, heparin, TNFa. This results in wheal, flare and oedema (swelling).

Synthesis of lipid mediators: PGD2 and cysteneiyl leukotrienes.

Synthesis of cytokines: IL3,4,5,13, GM-CSF.

Infiltration of more neutrophils, eosinophils.

Question 6

What is the function of adrenaline in allergy treatment?

Answer 6

Reformation of tight junctions, relaxation of smooth muscles, accelerate HR.

Question 7

What is the signature cytokine in delayed type hypersensitivity type 4?

Answer 7

IFN-g.

Question 8

Explain the mechanism of Coeliac’s disease.

Answer 8

It is a sensitivity to gliadins.

Patients have genetic mutation whereby they have tissue transglutaminase that deaminates glutamine to becoming a glutamate.

As a result of glutamate, it binds to a particular molecule: HLA DQ2 (sensitisation phase). Once bound, gets presented to APC, activates CD4 gets Th1 response. And there will be damage to villi.