Lung immunology

Question 1

Give some examples of allergic airway diseases and where they effect?

Answer 1

Upper airways= Allergic rhinitis
Bronchi= Asthma
Alveoli= Allergic alveolitis

Question 2

What are the different types of immunological hypersensitivity (allergy) ?

Answer 2

IgE mediated, Atopic disorers = havfever(allergic rhinitis), eczema, asthma
Non-IgE mediated allergic diseases = farmer’s lung

Question 3

Define Allergy

Answer 3

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

Question 4

How does an allergen trigger an Acute allergic response?

Answer 4

Allergen triggers an inappropriate Th2 response, this causes B cells to make IgE against the allergen which then coats mast cells and basophils. On preexposure to allergen it binds to the IgE on the surface of the granulocytes and causes degranulation, resulting in the release of histamine and other inflammatory mediators (prostaglandins, leukotrienes)

Question 5

How does an allergen cause a chronic allergic response

Answer 5

It is taken up by antigen presenting cells and presented to Th2 cells that were involved in the initial response (memory cells). These then release Th2 cytokines and chemokines.

Question 6

What interleukins do CD4+ Th2 cells release and what is their effect:

Answer 6

IL-4 = IgE synthesis
IL-5 = Eosinophil development 
IL-9 = Mast cell development
IL-13 = IgE synthesis and airway hyperrresponsiveness

Question 7

Define Atopy

Answer 7

Hereditary predisposition to produce IgE against common environmental allergens

Question 8

How are allergic tissue reactions in atopic subjects characterised?

Answer 8

There is infiltration of Th2 and eosinophils

Question 9

What are some common triggers for allergic Rhinitis?

Answer 9

Pollens (grass, tree weed), house dust mites, dogs, cats, alternaria (a type of fungi) , cockroaches

Question 10

What are the symptoms of asthma?

Answer 10

Cough, shortness of breath, wheezing, chest tightness, secretions(mucus)

Question 11

What is the mechanism for allergic alveolitis?

Answer 11

Small allergens (less than 5 microns) penetrate to the distal airways and alveoli. This is in close proximity to capillary so allergen comes in contact with IgE and forms a complex, triggering the immune response.

Question 12

What are the Principles of treatment of allergic diseases?

Answer 12

Allergen avoidance
anti allergic medication
immunotherapy

Question 13

What is the hygiene hypothesis?

Answer 13

Increase in atopy or allergy in a population could be due to increased hygiene and lack of microbial exposure.

Question 14

What are potential mechanism of immunotherapy in allergy treatment?

Answer 14

It could either up regulate Th1 cells, up regulate Treg cells or down regulate the Th2 cells causing the allergic reaction