Hypersensitivity

Question 1

Define hypersensitivity

Answer 1

An abnormal or exaggerated reaction to the ingestion, inflation or contact with a substance that does not provoke such a reaction in most people

Question 2

What is an allergic reaction?

Answer 2

A hypersensitivity reaction to a normally innocuous substance that is mediated by the immune system

Question 3

What can a person with mercury allergy experience

Answer 3

Burning mouth syndrome

Question 4

List the different classifications of hypersensitivity reactions

Answer 4

Type I
Type II
Type III
Type IV

Question 5

What are hypersensitivity reactions grouped according to?

Answer 5

1. The Immune effector mechanisms that mediate the response e
2. The type of antigen that stimulates them

Question 6

What are type I hypersensitivity reactions mediated by?

Answer 6

IgE and mast cells

Question 7

Before having a type I hypersensitivity reaction what must an individual be?

Answer 7

Must be sensitised

Question 8

What is the antigen associated with type I hypersensitivity reactions?

Answer 8

Any soluble antigen

Question 9

Talk through the steps of a type I hypersensitivity reaction

Answer 9

1. Soluble antigen is picked up by dendritic cells
2. Dendritic cell primes immune response, plasma cells migrate to mucosa and release allergen specific IgE
3. IgE binds to mast cells via the Fc region of the antibody binding to Fc receptors on mast cells
4. Following re exposure allergic binds to and clusters the IgE on the mast cell
5. This signals the FcR triggering mast cell degranulation releasing histamine

Question 10

What is the overall effect of a type I hypersensitivity reaction?

Answer 10

Mast cell activation, degranulation and the release of histamine

Question 11

Give some examples hypersensitivity reactions

Answer 11

1. Allergic reactions
2. Allergic asthma a
3. Atopic eczema
4. Anaphylaxis
5. Some drug allergies

Question 12

What is another name for type IV hypersensitivity reactions

Answer 12

Delayed type hypersensitivity reactions

Question 13

What is type IV hypersensitivity mediated by?

Answer 13

T cells

Question 14

Name the different T cells that can cause type IV hypersensitivity ?

Answer 14

Th1
Th2
Cytotoxic T cells

Question 15

What is the antigen associated with type IV hypersensitivity reactions?

Answer 15

Soluble antigen

Question 16

What are allergens?

Answer 16

Small and highly reactive molecules that bind to and immunologically alter host proteins

Question 17

What are the two stages of a type IV hypersensitivity reactions

Answer 17

Sensitisation

Elicitation

Question 18

Give examples of type IV hypersensitivity reactions that are mediated by Th1

Answer 18

Allergic contact Dermatitis

Tuberculin reaction

Question 19

Give examples of type IV hypersensitivity reactions that are mediated by Th2 cells

Answer 19

Chronic astma

Chronic allergic rhinitis

Question 20

Give examples of type IV hypersensitivity reactions that are mediated by Cytotoxic T cells

Answer 20

Graft rejection

Allergic contact dermatitis to poison ivy

Question 21

What is the effect of a type IV hypersensitivity reaction mediated by Th1 cells

Answer 21

Macrophage activation

Question 22

What is the effect of a type IV hypersensitivity reaction mediated by Th2 cells

Answer 22

IgE production
Esinophil activation
Mastocytosis

Question 23

What is the effect of a type IV hypersensitivity reaction mediated by cytotoxic T cells

Answer 23

Cytotoxicity

Question 24

Name three dental allergens

Answer 24

1. Latex
2. Antibiotics
3. Dental materials/ metals

Question 25

What is the most common problems associated with latex

Answer 25

1. Contact dermatitis and delayed type IV hypersensitivity | 2. Type 1 IgE mediated response (More serious)

Question 26

What are some of the symptoms of a latex allergy?

Answer 26

1. Mild irritation of mucosa 2. bronchospasm, 3. airway oedema 4. vasodilation resulting in hypotension.

Question 27

When can a type IV latex allergy start to show symptoms and list some of the symptoms

Answer 27

Symptoms can start to show 24+ hours after contact | Symptoms include: erythema, pruitis, eczema and vesicles

Question 28

When can a type I latex allergy start to show symptoms and list some of the symptoms

Answer 28

Symptoms can start to show mins- hours after contact | Symptoms include: erythema, pruitis, eczema, bronchospasm, vomiting, vasodilation, hypotension and death

Question 29

What is the frequency of penicillin allergy in dental patients

Answer 29

1 in 10 frequency

Question 30

What type of hypersensitivity reaction can antibiotic allergy cause?

Answer 30

Type II | cutaneous, non-IgE mediated rash

Question 31

What can some antibiotic allergies lead to

Answer 31

1. cutaneous, non-IgE mediated rash 2. Loss of red blood cells or neutrophils. 3. hives or possible anaphylaxis.

Question 32

After placing amalgam restorations what has been seen in a small proportion of patients

Answer 32

Delayed hypersensitivity reactions such as lesions with erythema and pruritic (itch) on the oral mucosa and oral lichen planus

Question 33

What is burning mouth syndrome an allergic reaction to?

Answer 33

Mercury

Question 34

List some metals people may be allergic to

Answer 34

1. Mercury 2. Nickel 3. Chromium 4. titanium

Question 35

List some clinical manifestations of nickel allergy

Answer 35

1. gingival hyperplasia, 2. numbness 3. burning sensations.

Question 36

In whom is a titanium allergy common in?

Answer 36

patients with pacemakers