Hypersensitivity reactions

Question 1

What is a hypersensitivity reaction?

Answer 1

Antigen-specific immune responses that are either inappropriate or excessive and result in harm to the host

Question 2

Name 2 intrinsic agents

Answer 2

Infectious microbes (mimicry) and self antigens (auto-immunity)

Question 3

What are the 4 types of sensitivity reaction?

Answer 3

Allergy, antibody mediated, immune complex mediated, cell mediated(delayed)

Question 4

Which Immunoglobulin is a type 1 reaction?

Answer 4

IgE

Question 5

Which immunoglobulin is a type 2 reaction?

Answer 5

IgG (sometimes IgM)

Question 6

What is the sensitisation phase?

Answer 6

First encounter with an antigen, activation of APCs and memory effector cells. After this the individual is “sensitised”

Question 7

What does a type 2 sensitivity reaction target?

Answer 7

Cell bound antigens

Question 8

What is haemolytic disease of the newborn?

Answer 8

When the mother is Rhesus -ve and the fetus is rhesus +ve, the mother develops antibodies that wil cross the placenta and damage fetal red blood cells. (only of a further child, not the first)

Question 9

What medication is given in myasthenia gravis?

Answer 9

Pyridostigmine (AChE inhibitor)

Question 10

What is plasmapheresis therapy?

Answer 10

Plasma is separated from blood and harmful antibodies removed, for short term relief and allows healing of damaged tissue

Question 11

What does a type 3 reaction target?

Answer 11

Soluble antigens

Question 12

How is tissue damage caused in a type 3 reaction?

Answer 12

Deposition of immune complexes

Question 13

Which type of immune complex is most difficult to remove?

Answer 13

Intermediate
Small= removed by macrophages
Large= removed by opsinisation

Question 14

What diseases are caused by type 3 hypersensitivity reactions?

Answer 14

Rheumatoid arthritis, glomerulonephritis, systemic lupus erythematous

Question 15

What diseases are caused by type 4 hypersensitivity reactions?

Answer 15

Contact hypersensitivity, granulomatous sensitivity, Hashimotos disease

Question 16

Give some examples of allergens?

Answer 16

Tree and grass pollen, house dust mite, fungal spores, insect venom, medicines, foods

Question 17

What is the abnormal adaptive immune response in type 1 reactions?

Answer 17

TH-2 response with IgE, normally a TH-1 response with IgG. Mast cells are activated

Question 18

What is the hygiene hypothesis?

Answer 18

Children exposed to animals and microbes in the early postnatal period appear to be protected against certain allergic diseases

Question 19

What is the old friend hypothesis?

Answer 19

Western lifestyle induces alteration of the symbiotic relationships with parasite and bacteria leading to alterations of the microbiome

Question 20

What can be measured for anaphylactic shock?

Answer 20

Tryptase

Question 21

What are the signs and symptoms of systemic mast cell activation?

Answer 21

Hypotension, cardiovascular collapse, angioedema, breathing problems

Question 22

What does there have to be for it t be anahylaxis?

Answer 22

Acute onset, rapidly progressing, skin and another system. If known to have anaphylactic reaction skin doesn’t have to be involved