Allergies

Question 1

Define Allergy

Answer 1

Exaggerated immune response to a non-microbial/environmental antigen

Question 2

What antibodies are overproduced to cause Allergies?

Answer 2

Immunoglobulin E (IgE) antibodies

Question 3

What are cytokines IL-4, 5 and 13 produced by?

Answer 3

Th2 cells, Mast cells and eosinophils

Question 4

Define Atopy and name the type of disorders is it associated with?

Answer 4

Atopy is a genetically determined, exaggerated IgE-meditated immune response and is it’s associated with Type 1 hypersensitivity disorders such as asthma and hay fever.

Question 5

What is Asthma? State it’s symptoms and cause.

Answer 5

Asthma is a chronic disorder of the airways with variable airflow limitation. Recurrent episodes of wheezing, breathlessness and cough.

Cause by inhaled allergens.

Question 6

What is Rhinitis? State it’s symptoms.

Answer 6

It is a respiratory disease linked to asthma and it causes nasal congestion, itching and sneezing.

Question 7

What is angioedema and urticaria? State the triggers.

Answer 7

Raised itchy, nettle rash such as hives and it is triggered by food and drug allergens such as ACEIs and NSAIDs.

Question 8

Define Eczema.

Answer 8

It is a local inflammation of the skin that appears in early childhood induced by food such as egg and milk.

Question 9

What is Anaphylaxis? State it’s triggers.

Answer 9

It is a sever allergic reaction which can be life threatening. It’s triggers are food, drugs such as antibiotics, latex and venom.

Systems involved - gastro, cardio, blood and respiratory

Question 10

Describe Genetic Predisposition.

Answer 10

It is influenced by inheritance of several genes and chromosomes. The identification of susceptibility locus for Atopy on chromosome 5q, near the site of gene clusters encoding cytokines IL-4,5,9 and 13.

Question 11

What is the Hygiene Hypothesis?

Answer 11

The cleaner the environment the less microbes.

Question 12

Describe the Skin Prick Test.

Answer 12

Test selects allergens based on clinical history.

A drop of allergen on skin - small skin prick = skin reaction which results in local tissue swelling and degranulation.

Question 13

What would diminish the sensitivity of the Skin Prick Test?

Answer 13

If the patient takes any antihistamines.

Question 14

What are the controls in the Skin Prick Test?

Answer 14

histamine - positive

Saline - negative

Question 15

What is Allergen Sensation? State the 2 events.

Answer 15

Exposure of allergen leading to an increase in IgE production.

1. Differentiation of at T cells to Th2
2. Stimulate B cells to switch to IgE production - Th2 cells produce cytokines and provide the CD40 ligand to lead antibody Class switching.

Question 16

What are Mast Cells and Basophils?

Answer 16

They initiate an acute inflammatory response.

Basophils - reside in circulation
Mast Cells - function as immune sentinel cells and produce cytokines.

Question 17

Where are Mast Cells found?

Answer 17

They are found in the connective tissue surrounding blood vessels and mucosal surfaces.

Question 18

What are the granule contents of Mast Cells?

Answer 18

Histamine
Leukotrienes
Inflammatory cytokines
Neutrophils and eosinophils attracting cytokines

Question 19

What is the granule content of Eosinophil?

Answer 19

T and B cell attracting chemokines
Fibrotic cytokines
Matrix metalloproteinases and collagenases

Question 20

Describe the Early phase of an allergic response.

Answer 20

Physiological mechanisms and loss of organ function due to mucus production, vasodilation & swelling and bronchoconstriction.

Question 21

Describe the Late phase of an allergic response.

Answer 21

Immunological mechanisms
Smooth muscle scarring
Recruitment of Immune cells into peripheral tissue

Question 22

Describe the immediate phase of an allergic reaction.

Answer 22

Mast cell degranulation

Histamine release