13 - Lung Immunology: Allergic Airway Disease

Question 1

Give an allergic airway disease of the:

1) upper airways
2) bronchi
3) alveoli

Answer 1

1) allergic rhinitis (hayfever)
2) asthma
3) allergic alveolitis

Question 2

What is hypersensitivity (simply put)?

Answer 2

an exaggerated response (that can be immunological or non-immunological)

Question 3

What is allergy?

NOTE: it is a mechanism NOT a disease

Answer 3

an exaggerated immunological response to a foreign substance (allergen) which is either inhaled, swallowed, injected or comes into contact with the skin or eyes

Question 4

What types of microorganisms to Type 1 and Type 2 helper T cells target?

Answer 4

Th1 cells - viruses, bacteria, fungi and protozoa

Th2 cells - helminths (worms) and ectoparasites (ticks)

Question 5

Give the mechanism of action behind IgE-mediated allergic reactions
( acute and chronic)

Answer 5

ALL ABOUT IGE ANTIBODIES

• IgE antibody is produced by B-cells with the help of Th2 cells
• IgE enters the blood and goes into the tissues, where It binds to the surface of granulocytes such as basophil;s and mast cells
  NOTE: basophils are in your periphery (blood) and mast cells are in tissues (e.g. mucosal surfaces, gut etc)
• IgE binds to mast cells and remains bound for a very long time
• when the same allergen is next encountered, the allergen will cross-link IgE on the mast cell —–> mast cell degranulation (histamine release)

NOTE: this is responsible for acute symptoms of allergy
THIS IS THE IMMEDIATE RESPONSE

• the allergen will also bind other receptors
• it will be bound by the same specific Th2 cell —–> cloning —–> production of Th2 cytokines and chemokines
  NOTE: this brings about the chronic symptoms of allergy

Question 6

TH2 cells (are CD4+ cells) and release the following interleukins:
IL-4
IL-5
IL-9
IL-13
What is action of these interleukins?

Answer 6

IL4 - IgE synthesis (class switching to B-cells)
IL-5 - eosinophil development (from precursors)
IL-9 - mast cell development
IL-13 - IgE synthesis and airway hyperresponsiveness

Question 7

State 3 atopic diseases

Answer 7

allergic rhinitis, asthma and atopic eczema

Question 8

What is the difference between atopy and allergy?

Answer 8

allergy is the biological repines of atopy

atopy is the presence of IgE in the blood

Question 9

Define atopy

Answer 9

the hereditary predisposition to produce IgE antibodies against common environemnal allergens

Question 10

What cells are characteristic of allergic tissue reactions?

Answer 10

Th2 cells and eosinophils

Question 11

What is meant by the ‘allergic march’?

Answer 11

the common progression of atopic disease from atopic dermatitis to allergic asthma

Question 12

What are the symptoms of allergic rhinitis?

Answer 12

blocked or runny nose, sneezing, itchy and streaming eyes

Question 13

What is the link between allergic rhinitis and hayfever?

Answer 13

hay fever is seasonal allergic rhinoconjunctiviitus

Question 14

What is seasonal allergic asthma?

Answer 14

when the pollen counts are very high, some wheeziness can co-exist which rhinitis

Question 15

What are the 2 types of allergic rhinitis?

Answer 15

seasonal or perennial (all year - can be due to household allergen)

Question 16

What are some of the non-allergic causes of perennial rhinitis?

Answer 16

infection and structural abnormalities (and some have underlying immunodeficiency problems)

Question 17

Which part of the airways is affected by asthma?

Answer 17

BRONCHI

the lower airways - lung, trachea, bronchi, bronchioles

Question 18

Define asthma

Answer 18

a chronic disorder characterised by episodes of wheezy breathlessness, but which may also be present as an isolated cough, particularly in children

Question 19

Asthma is a very heterogenous disease. What is meant by this?

Answer 19

there are many phenotypes

Question 20

What are the 3 types of asthma, based on control and severity?

Answer 20

• intermittent, mild - allergy is frequently important
• persistant, mangeable - allergy is important
• chronic, severe - uncontrolled by treatment

Question 21

What are the 3 types of asthma, based on end-type or endo-phenotype?

Answer 21

• allergic/atopic/eosinophilic
• neutrophilic
• exercise induced

Question 22

What is general anaphylaxis?

Answer 22

systemic manifestation of allergic reaction

Question 23

Give some possible symptoms of general anaphylaxis

Answer 23

• dizziness, seizure, loss of consciousness
• anxiety, sense of gloom
• arrhythmia
• vomiting, diarrhoea and pain
• urticaria
• tingling in hands and feet
• bronchoconstriction
• laryngeal oedema