Allergy 2 Flashcards
What is atopy
- Genetic predisposition to develop IgE antibodies against common environmental antigens
What are the clinical correlates of atopy
- Hayfever
- asthma
- atopic eczema
- increased likelihood of developing allergic urticaria
- angioedema
- anaphylactic shock
Out of TH1/TH2 which one is more dominant
TH2 is more dominant in atopic individuals
you do not need to be atopic to develop
anaphylactic shock
what type of hypersensitivity are allergic conjunctivitis, rhinitis, sinusitis
- Type 1 hypersensitivity - IgE mediated
What antigens are responsible for allergic conjunctivitis, rhinitis, sinusitis
- Grass pollens, tree pollens. Seasonal exposure.
- Animal danders.
- House dust mite
How do you diagnose allergic conjunctivitis, rhinitis, sinusitis
- history.
- If seasonal: pollens, hayfever.
- Skin prick tests and specific IgE confirmatory, but history is main thing! May develop nasal polyps
What is the treatment of allergic conjunctivitis, rhinitis, sinusitis
Treatment
- topical or systemic antihistamines
- topical mast cell stabilisers e.g. disodium chromoglycate
- topical steroids
- antigen exclusion
What are other causes of rhinitis and sinusitis
- Viral and bacterial infections: common. Leprosy (rare).
- Vaso-motor rhinitis
- Non-allergic rhinitis with eosinophilia (NARES)
- Drug induced: alpha agonist sprays, cocaine abuse.
- Irritant fumes & solvents
- Vasculitis, Wegener’s granulomatosis.
- Septal deviation, foreign bodies.
- Late pregnancy (oestrogens)
- CSF leak.
what can cause asthma
- Allergy & Th1/Th2,
- neurogenic
- smooth muscle factors,
- irritants
- occupational exposure,
- acute & chronic inflammatory response characteristics all important.
what type of asthma is allergy more important
- Allergy is more important in childhood asthma especially if there are other atopic features such as antigens pollens, animal danders, HDM
What can trigger asthma allergies
- antigen pollens
- animal dangers
- HDM
- acute bronchospasm
what are the treatments of asthma
- Topical (inhaled) beta 2 agonists
- topical (inhaled) steroids
- nebulised theophylline
- systemic steroids
- monoclonals against IL4R , IL5, IL5R
- ventilation in extremis
What happens in atopic dermatitis
- Dry cracked very itchy raised lichenified weeping lesions.
- Initially may be on extensor surfaces, then flexures, also cheeks.
What mutation is involved in atopic dermatitis
- filaggrin mutation appear to predispose to dermatitis
how much does IgE raise in atopic dermatitis
IgE often raised 1000ku/l (NR <81)
what markers are increased in atopic dermatitis
- IgE
- eosinophils
- mast cells
- Langerhan cells in skin express Fc elipson
What can cause aspirin sensitivity
- aspirin can cause angioedema like other NSAIDS
- since prostaglandin formation is blocked there is a deviation towards leukotriene formation
What is the triad of symptoms you get with aspirin sensitivity
- asthma
- nasal polyps
- sinusitis
How do you treat aspirin
- Polyps may need surgery or topical steroids
- avoid aspirin and salicylates
What food contain salicylates
- tea
- coffee
- herbs and spices
- black pepper
- sharp green apples
- cherries
- strawberries
- dried fruit
- tomatoes
- fruit juices
- cider
- wine
- peppermints
- liquorice
aspirin can enhance the ability of…
Aspirin can enhance the ability of other allergens to cause anaphylaxis.
What is oral allergy syndrome
Itching and local swelling in oropharynx within minutes of eating food. Rarely may progress to urticaria & angioedema of face, and even anaphylaxis.
What type of hypersensitivity in oral allergy syndrome
Mediated by specific IgE: type I hypersensitivity
Describe what food types cause oral allergy syndrome
- Birch pollen allergy + hazelnut, apple, pear, carrot.
- Birch pollen allergy + plums, peaches, cherries, almonds.
- Ragweed allergy + melon, banana.
- Grass pollen allergy + tomato, melon.
- Mugwort pollen allergy + celery, carrot, spices.
What is the treatment of oral allergy syndrome
- Avoid foods
- mostly heat labile so cooked ok
what are other symptoms of food allergy that do not cause oral allergy
- gut (abdo pain, diarrhoea, vomiting),
- skin (urticaria & angioedema) - respiratory tract (bronchospasm and angioedema).
- Should follow ingestion of food in minutes - an hour or two.
- May cause anaphylaxis.
what can food allergy cause in the gut
- eosinophilic gastropathy
- enteritis
What foods tend to cause food allergy
Peanuts & other legumes. True nuts – walnuts, cashew, almond, hazelnut. Shellfish & fish. Egg, milk. Latex, banana, avocado, kiwi, chestnut, potato, tomato. Omega gliadin.
How do you treat food allergy that is not in the mouth
- avoidance
- Steroids for eosinophilic enteritis.
what are skin prick tests useful in
- milk
- egg
- fish
- peanut
- true nuts
What is latex present in
- gloves
- many medical products
- condoms
What does latex cross react with
Cross- reaction with bananas, avocado, Kiwi.
What type of hypersensitivity is latex
IgE type 1 hypersensitivity
What are the symptoms of a latex allergy
- Contact urticaria,
- rhino-conjunctivitis,
- asthma,
- angioedema, anaphylaxis
How do you test for latex allergy
Skin prick tests and specific IgE tests against recombinant antigens
What is the treatment for a latex allergy
- avoidance
- Hospital environment difficult.
what can happen in a drug allergy
- fevers
- fixed drug reactions - a rash on the skin in a particular place where you have the drug
- stevens-johnson syndrome
- erythema multiforme
what hypersentivities can penicillin cause
- Type I hypersensitivity: anaphylaxis
- Type II haemolytic anaemia.
- Type III Serum sickness
- Type IV interstitial nephritis.
How do you test for penicillin allergy
For IgE against penicillin, test for antibodies, skin prick tests, desensitisation possible
what other drugs can cause allergies
co-trimoxazole in AIDS, rash, IgE to sulphonamide.
describe what happens in an insulin allergy
- if the manufacturing produces a slightly altered insulin structure then antibodies can develop towards insulin
- local urticarial
- induration
- may get some general anaphylactic type symptoms
what do you do if patient has allergy to anaesthetics
- measure tryptase
- save serum
What is DRESS syndrome and its symptoms
Drug reaction with eosinophils & systemic symptoms.
- After several weeks: fever, rash, lymphadenopathy. Liver, kidney or lung, eosinophilia, lymphopenia or lymphocytosis, thrombocytopenia
What type of hypersensitivity is extrinsic allergic alveolitis
Type III Hypersensitivity
describe extrinsic allergic alveolitis
- Inhaled foreign antigens, occupational exposure.
- Animal, fungi, bacterial plant, chemical.
- Eg bird fanciers’ lung, farmers’ lung (fungi).
- Symptoms start about 6 hours after exposure & often worst at 24-48 hours. Fever, cough, shortness of breath.
- May have asthma as well: type I hypersensitivity.
- May develop type IV hypersensitivity as well. Chronic exposure leads to worsening interstitial pulmonary disease.
What hypersensitivity is allergic bronchopulmonary aspergillosis.
Type III & type I reaction to Aspergillus
What are the symptoms of allergic bronchopulmonary aspergillosis
- Wheeze
- cough
- fever
- haemoptysis
what can develop in allergic bronchopulmonary aspergillosis
Bronchiectasis may develop.
what antibodies rise in response to allergic bronchopulmonary aspergillosis
High IgG & IgE to Aspergillus.
What type of hypersensitivity is serum sickness
Type III hypersensitivity
What can cause serum sickness
Infused human serum or serum products eg IVIG, monoclonal antibodies, and any drug that can bine to patients’ own proteins, altering the (eg penicillin)
what are the symptoms of serum sickness
- Fever
- poly-arthritis
- vasculitis
- lymphadenopathy
- urticarial
When does serum sickness first show
7-14 days after primary exposure, 1-3 days after secondary exposure.
What type of hypersensitivity is contact hypersensitivity
Type IV hypersensitivity
describe the types of contact hypersensitivity
- Nickel “allergy”
- Topical drug applications
- Aniline dyes in leather.
- Chromium from cement: builders.
- Latex & rubber material: various chemicals.
- Hair dyes, fragrances, cosmetics.
- Plants: ivy, sumac, chrysanthemum.
- Exposure to sunlight may be required to trigger sensitivity
What tests do you carry out for allergies
- First take a good history!
- Skin prick tests.
- Specific IgE in vitro tests.
- Autoantibody screen etc.
- Patch testing.
- Tryptase
- D-dimers - also rises in angioedema
- Complement: C1 esterase inhibitor quantity and function. C3 & C4, C1q, C2, autoantibodies to C1q.
what is the mainstay of treatment in allergies
- antihistamines against H1 receptor
What does ranitidine do
- antihistamine against H2 receptor
What is disodium chromoglycate used in
- mast cell stabiliser
- used as drops in allergic rhinitis and conjunctivitis
name the monoclonal antibodies used in allergies
Dupilumab (monoclonal against IL4 receptor)
Mepolizumab (monoclonal against IL5)
Benralizumab (monoclonal against IL5 receptor)
- used in asthma and eczema
