12- Lung Immunology And Allergic Airway Disease

Question 1

Define allergy, hypersensitivity, atopy, intolerance

Answer 1

“Hypersensitivity-An umbrella term to describe an exaggerated sensitivity to any agent irrespective of the mechanism.
Allergy - An exaggerated sensitivity resulting from a heightened or altered reactivity of the immune system in response to external substances
Atopy - An hereditary predisposition to produce specific IgE antibodies to common aeroallergens
Intolerance - The presence of symptoms following environmental exposure and/or food ingestion where an immunological mechanism cannot be established.
”

Question 2

Give 3 examples of IgE-mediated atopic disease

Answer 2

Hay fever,eczema, asthma

Question 3

Give examples of t helper type 1 cells and antibody subclasses

Answer 3

Th17 cells, NK cells, cytotoxic T cells,

IgM, IgA and IgG antibody subclasses

Question 4

Th2 cell types and antibodies

Answer 4

IgE and IgG1 antibodies epithelial barriers, innate lymphoid cells, eosinophils, mast cells, basophils, activated macrophages.

Question 5

Describe acute and chronic igE mediated allergic reactions

Answer 5

Acute: igE antibody mast cell binds to antigen, mast cell degranulation, histamine release , acute symptoms
Chronic: Th2 cells release cytokines and chemokines

Question 6

What are the 4 interleukins released by CD4+ th2 cells

Answer 6

4- igE synthesis
5- eosinophils development
9- mast cell development
13- igE synthesis and airway hyperesponse

Question 7

Describe Seasonal Allergic Conjunctivo-rhinitis (Summer Hay Fever)

Answer 7

-Effects 12-15% children, 11-17% adults -UK prevalence highest in Europe -Effect on school exams, time off school

Question 8

What is extrinsic allergic alveolitis

Answer 8

Small allergenic particles (less than 5 microns) penetrate to the distal airways and alveoli
Affects 0.1% of population
E.g. farmers lung

Question 9

What factors may have increased allergy prevalence

Answer 9

Microbial
Water sanitation (less oro-faecal water born infections)
Food quality (lack of fermenting bacteria, more processed foods) Poverty (high asthma rates in the urban underprivileged) Medical interventions (antibiotics in childhood,vaccines

Non-microbial
Pollution (air, water, food)
Diet and nutrition (lack of Vit D, fish oil, omega 3 fatty acids, trace elements)
Obesity (may cause chronic inflammation)
Climate change (high pollen counts)
Stress (linked to chronic inflammation) Genetics/epigenetics

Question 10

How can immunotherapy treat allergy

Answer 10

• Immunotherapy is one form of intervention for allergic diseases. This involves changing the immune response, encourage a Th1 (or T reg) response and discouraging a Th2 response through careful administration of low levels of allergen

Question 11

Which type of cells mediate allergic response

Answer 11

• Allergies are mediated by Th2 cells that illicit an IgE antibody response, and involve early phase (mast cell) and late phase (T cell) reactions

Question 12

What are the 3 endotypes of asthma

Answer 12

allergic, atopic or eosinophilic asthma

• neutrophilic asthma
• exercise induced asthma