Hypersensitivity

Question 1

Exagerated immune response rather than Ag itself is damaging

Answer 1

Bystander damage

Question 2

Which types are Ab-mediated?

Answer 2

I, II, III

Question 3

Which type caused by inappropriate act of Th1?

Answer 3

IV

Question 4

Increased IgE (dys reg of Th cells - drives B cells to make IgE) against eAg
Immediate onset
Most common
also called allergy

Answer 4

Type I hypersensitivity

Question 5

Increased IgE = symptoms = clinical disorder

Type 1

Answer 5

Allergy

20-30%

Question 6

Increased IgE = no related symptoms = sub-clinical immune sensitisation
Type 1

Answer 6

Atopy

larger proportion = 40-50%

Question 7

vasodilation
secretions
capillary leakage
Mucosal oedema
smooth muscle contraction

Answer 7

Effects of Type 1

Question 8

Type 1 - release of pre formed inflamm mediators

Answer 8

histamine and herparine

Question 9

Type 1 - release of newly synthesised inflamm mediators

Answer 9

PGs and leukotrienes

Question 10

IgG or IgM Ab against sAg / Ag fixed within tisc
wrong blood donation - kill patients
Ag: exogenous (hypersensitivity) vs self (autoimmune)? = same tissue damage mech

Answer 10

Type 2

1. Ab:Ag complex
2. complement
3. Fc binding of Ig - phagocyte stimulation
4. ADCC
5. effects on target cell function - inhibition of func + stimulation

Question 11

Type 2 - ADCC

Answer 11

Ab dependant cellular toxicity

Question 12

abnormal deposition of formed Ag:Ab complex in tisc

exogenous or self Ag

Answer 12

Type 3

Question 13

Immune complex formation - physiological, pathological or both?

Answer 13

Both

Question 14

In type 3, the end result of abnormal immune complex formation is…….

Answer 14

Precipitation of complexes out into tisc and cause inflamm

Question 15

In type 3, Immune complexes deposited in many tisc

Answer 15

systemic illness (serum sickness)

serum - everywhere

Question 16

In type 3, Immune complexes form locally in tisc

Answer 16

localised disorder (arthus reaction)

arthritis - localised in joints

Question 17

Delayed type hypersensitivity
no detectable Ab
Th1 cells + cytokine (mainly IL2 & gamma-interferon)
Reactions take place as body finds it hard to destroy

Answer 17

Type 4

Question 18

low MW agent - Type 4

Answer 18

Hapten

Question 19

Carrier (type 4 hypersensitivity)

Answer 19

host protein

Question 20

Immune response itself is the cause of tisc damage

T or F?

Answer 20

T

E.g. Type 4 hypersensitivity = mycobacteria not cytotoxic, do not produce toxins