CP5-1 allergic diseases Flashcards
What are symptoms of rhinitis?
Blocked/runny/itchy nose
Sneezing
Often with eye symptoms - itching, burning, redness, watery eyes
What are the two types of allergic rhinitis?
Seasonal
Perennial
What causes seasonal allergic rhinitis?
Pollen
Moulds
What causes perennial allergic rhinitis?
House dust mite
Animal dander
What causes non-allergic rhinitis?
Vasomotor changes
Infection
Structural changes
Drugs
Hormones
Polyps
How is rhinitis treated?
With antihistamines and intranasal steroids
What is asthma?
A disease of inflammation and hypersensitivity of small airways
What causes asthma in childhood?
Aero-allergic stimuli like house dust mites
What type of hypersensitivity causes anaphylaxis?
Type I
What hypersensitivity reactions are caused by IgG antibodies?
Type II and III
How do IgE antibodies cause allergic reactions?
Binding to mast cells
What immunoglobulin causes the immediate symptoms of asthma?
IgE
Fill in the blank.
Damaged airways due to asthma are ____________________ to non-allergic stimuli e.g. fumes.
Hyper-reactive
What is the pathogenesis of asthma?
Allergen taken up by antigen presenting cell which binds to Th2 cell. IL-4 and IL-13 convert Th2 into B cells/plasma cells resulting in release of IgE. IgE binds to mast cells/basophil
Where do asthma drugs target in the pathway?
G protein-coupled receptors (GPCRs)
What are the three types of dermatitis?
Eczema
Contact
Other types
What are the two subtypes of eczema?
Atopic
Non-atopic
What three conditions form the atopic triad?
Eczema
Asthma
Hay fever
What are the two sub-types of contact dermatitis?
Allergic
Non-allergic
What are symptoms of eczema?
Intense itching
Blistering/weeping
Cracking of skin
What is a major trigger for atopic eczema?
House dust mite
What three factors interplay with eczema?
Skin barrier
Pruritus/scratching
Allergy
What is the pathway of sensitisation and memory induction?
Allergen binds to dendritic cell —> T cell binds to dendritic cell via MHC II molecule —> T cell differentiates into T helper 2 cell and there’s clonal expansion —> T helper 2 cells trigger memory B cells to produce IgE —> there is IgE memory B cell clonal expansion
What is the pathway of immediate phase/type 1 reaction response?
IgE released by B cells binds to mast cells + allergen binds to basophils —> degranulation + release of vasoactive amines, lipid mediators, chemokines and other cytokines
What is the pathway of late phase/allergic inflammation?
T helper cells:
- activate eosinophils to release mediators, chemokines and inflammatory cytokines
- initiates smooth muscle cells to contract and release chemokines and pro-inflammatory cytokines
- increased adhesion of endothelial cells and inflammatory cell transmigration
- initiates basophil entry into tissues and mast cell and basophil degranulation
- causes atopic dermatitis by inducing keratinocyte apoptosis and activating epithelial cells to release chemokines and pro-inflammatory cytokines
- causes allergic rhinitis and asthma by inducing increased mucus production, increased IgE production and induction of bronchial epithelial cell apoptosis.
Which cells secrete IgE?
Plasma cells
What are three specific IgE tests used?
Immulite 2000/Siemens
ImmunoCAP/ThermoFisher
Hytec 288 Plus/Hycor
What are the two types of ImmunoCAP? What are each used to test?
Extract - tests extraction of allergens raw material
Component - sets allergen raw material after recombinant technology or purification.
What are two skin tests used to test for allergies?
Skin prick test - >2mm wheal = positive
Intra-dermal
What are all the used tests for allergies?
Specific IgE tests
Skin prick tests
Intra-dermal tests
Basophil activation tests
Graded challenge test
What is a basophil activation test?
Patients basophil is exposed to allergen and then analysed for its response.
How do you treat allergies?
By symptoms - antihistamines, steroids, adrenaline
Immunotherapy
What allergic diseases benefit from immunotherapy?
Life threatening reactions to wasp and bee stings
Severe hay fever
Animal dander allergies
What allergic disease is immunotherapy not helpful in?
Multiple allergies
Food allergies
Eczema
Spontaneous urticaria (aka hives)
What is the gold standard test for allergies?
Graded challenge test
What is a graded challenge test for allergies?
A feeding test where allergen is consumed in gradually increasing amounts to diagnose or rule out a food allergy
What drug prevents skin prick tests from working?
Antihistamines
What are the two types of immunotherapy for allergies?
Subcutaneous
Sublingual
What cells does allergic-specific immunotherapy target?
Eosinophils and mast cells - reduces numbers and mediation release
T-cells - decreases their allergen specific proliferation, reduced number of T cells in late phase reaction, reduces number of t helper 1 and 2 cytokines in blood and T helper 2 in tissues (increased T helper 1 in tissues) + increases regulator T cells and IL-10
B-cells - reduction in allergen specific IgE and IgE facilitated antigen presentation , increase in IL-10 and blocking antibodies
Monocytes - increase IL-10 production
What are benefits of allergen-specific immunotherapy?
improved quality of life
Reduction of symptoms and drug/treatment use
Decrease in response to allergen-challenge test and skin prick test
Decrease in size and number of cells in late phase reaction
Prevents progression of allergy
Prevents new sensitisation
What are the two types of adverse food reactions?
Allergy
Intolerance
What are the two sub categories of food intolerance?
Caused by food characteristics
Caused by host characteristics
What are examples of food characteristics which cause intolerance?
Pharmacological e.g. contain caffeine
Toxin e.g. bacterial
What are examples of host characteristics that cause food intolerances?
Metabolic e.g. lactase deficiency
Psychological e.g. panic disorder
What are the three subtypes of food allergy?
IgE mediated
Mixed
Non-IgE mediated
What are examples of IgE mediated food allergic reactions?
Anaphylaxis
Urticaria (aka hives = raised itchy skin rash)
Angioedema (sudden swelling of part of the body)
Oral allergy syndrome (itchy mouth and throat after consumption of allergen)
Acute rhinitis
Acute asthma
What are examples of mixed food allergy reactions?
Atopic dermatitis
Eosinophillic esophagitis (inflammation of oesophagus)
Eosinophillic enteritis (infiltration in bowel wall)
What are examples of non-IgE mediated food allergies?
Contact dermatitis
Dermatitis herpetiformis
Proctocolitis (inflammation of rectum and colon)
FPIES (food protein-induced enterocolitis syndrome - usually affecting babies)
Coeliac disease
Heiner’s syndrome (a cow milk induced pulmonary disease mainly affecting infants)
What are the 6 major food allergens?
Cow’s milk
Egg
Legumes (peanut, soybean, tree nuts)
Fish
Crustaceans
Cereal grains
What are the clinical manifestations of adverse food reactions?
Gastrointestinal- vomiting, diarrhoea, oral symptoms
Respiratory - rhinitis, bronchospasm
Cutaneous - urticaria, angioedema
Anaphylaxis
What in a history will help with determining a drug allergy/what type of reaction it is?
Indication for the drug
Description of the reaction
Time between drug intake and symptom onset
Number of doses take before onset
Know the pharmacological effects of the drug
If a drug allergy is suspected, how is this managed?
Intradermal testing
Graded challenge
Desensitisation
