Allergy and Hypersensitivity

Question 1

Hypersensitivity occurs when the ________________________

Answer 1

Immune system over-responds to harmless antigens that result in harm to the body

Question 2

_________________mediated by the inappropriate production of specific IgE antibodies to harmless antigens (classical allergy)

Answer 2

Type I Hypersensitivity

Question 3

________________ caused by IgG and IgM antibodies that bind to antigens cells or tissues leading to cell or tissue damage

Answer 3

Type II Hypersensitivity

Question 4

________________ caused by antibody-antigen complexes being deposited in tissues, where they activate the complement system and cause inflammation

Answer 4

Type III Hypersensitivity

Question 5

_________________ caused by T helper cells traveling to the site of antigens, recruiting macrophages and causing inflammation

Answer 5

Type IV Hypersensitivity

Question 6

Type IV hypersensitivity reactions are a _____________________

Answer 6

Delayed type hypersensitivity reaction

Question 7

Allergens are ____________

Answer 7

Antigens that produce allergic reactions

Question 8

IgE mediated allergy is responsible for a number of atopic conditions such as………

Answer 8

Food or drug allergy
Asthma
Allergic rhinitis
Hayfever
Eczema

Question 9

___________________ is the initial event that lead to the specific IgE being developed for that allergen

Answer 9

Sensitisation

Question 10

Process of sensitisation……

Answer 10

CD4 cells recognise the allergen

They proliferate and differentiate into T Helper 2 cells

These Th2 cells release IL-4, that stimulates the production of IgE by B Cells specific to that allergen

The IgE then circulates the blood and binds to mast cells

Question 11

The Allergic Response involve activation of _______________

Answer 11

Mast cells

Question 12

Histamine causes ______________________, causing symptoms of allergy, this happens within ____________ of exposure to the allergen

Answer 12

Vasodilation, increased vascular permeability and broncho-constriction

Minutes

Question 13

TNF-α causes a ____________________at the site of exposure, this takes a ___________ and is called the _________________

Answer 13

Localised inflammatory process

Few hours

Late phase reaction

Question 14

Symptoms of allergy include…

Answer 14

Itch, flushing, rash, angioedema and wheeze

Question 15

T or F: Allergic responses to allergens tend to get worse on repeat exposures due to increased sensitisation

Answer 15

True

Question 16

________________ can be measured to confirm the diagnosis of anaphylaxis, and will be raised after an anaphylactic reaction

Answer 16

Mast cell tryptase

Question 17

Examples of Type II Hypersensitivity reactions

Answer 17

Blood transfusion reactions
Haemolytic Disease of the Newborn
Goodpastures Syndrome

Question 18

Examples of Type III Hypersensitivity reactions

Answer 18

Farmers lung
Rheumatoid arthritis

Question 19

In type II reactions it is the ____________________ that causes inflammation and damage of the target, whereas in type III, the __________________, and it is the _____________________ that travel to their target organs where they cause inflammation and damage

Answer 19

Antibodies binding to the target
Antibodies bind to antigens
Antibody-antigen complexes

Question 20

Type IV Hypersensitivity takes _____________ to occur

Answer 20

24-72 hours

Question 21

What happens in a Type IV Hypersensitivity reaction?

Answer 21

Antigens enter tissues and get picked up by dendritic cells that deliver them to relevant CD4 cells

CD4 cells proliferate and differentiate into T helper cells which then travel to the tissues where original antigen presented

T helper cells release cytokines that recruite macrophages and both cells release proinflammatory cytokines that result in localised inflammation

In skin this presents as a contact dermatitis

Question 22

Examples of Type IV Hypersensitivity reactions

Answer 22

Contact with Poison Ivy
Contact with Nickel and gold
Mantoux test