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

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


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

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


Define Allergy

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


How does an allergen trigger an Acute allergic response?

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)


How does an allergen cause a chronic allergic response

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.


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

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


Define Atopy

Hereditary predisposition to produce IgE against common environmental allergens


How are allergic tissue reactions in atopic subjects characterised?

There is infiltration of Th2 and eosinophils


What are some common triggers for allergic Rhinitis?

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


What are the symptoms of asthma?

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


What is the mechanism for allergic alveolitis?

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.


What are the Principles of treatment of allergic diseases?

Allergen avoidance
anti allergic medication


What is the hygiene hypothesis?

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


What are potential mechanism of immunotherapy in allergy treatment?

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