allergy Flashcards

Question

sx not associated with IgE allergic reactions

Answer 1

Fatigue Migraine (food can cause it – but it is because of high tyramine – not an allergy!!) Recurrent abdominal pain, diarrhoea, constipation, bloating Hyperactivity Depression Symptoms which vary over time, with antigen dose and source

Answer 2

Presence of IgE - necessary not sufficient for allergic disease sensitisation is more common than allergic disease hx determine what tested for on blood test if right hx - large skin wheals and high blood IgE - more likely associated with allergy results of skin prick, or serum IgE dont predict reaction severity

Answer 3

standard soln of allergen extract through skin prick to the forearm positive control - histamine -ve control - diluent measure wheal Antihistamines and some anti-depressants should be discontinued for at least 48 hours beforehand IgE cross linking on mast cells -> degranulation and release of histamine and inflammatory mediators

Answer 4

wheal ≥ 3mm greater than the negative control has high +ve and -ve predictive value for aeroallergens

Answer 5

Rapid (read after 15-20 minutes) Cheap and easy to do Excellent negative predictive value usually more than > 95% Increasing size of wheals correlates with higher probability for allergy Patient can see the response

Answer 6

Requires experience to interpret Risk of anaphylaxis: 1 in 3000 Poor positive predictive value: high false positive rate Limited value in patients with dermato-graphism or extensive eczema False negative results with labile commercial food extracts

Answer 7

positive, negative controls and allergens into the skin more sensitive, less specific than SPT best used to follow up negative venom and drug allergy test - better than blood tests use if -ve SPT but convincing hx labour intensivce more anaphylaxis risk

Answer 8

Detection of IgE to whole allergen extract or to individual protein (component) with in an allergen extract automated assays

Answer 9

* Detection of IgE antibody with little clinical relevance * Allergen in low abundance may lead to reduced sensitivity * Clinical utility and cost of multiplex assay remain to be determined * Limited understanding of their role in diagnosis of allergic disorder outside of allergist/immunology specialists

Answer 10

Abundance and stability of individual protein within allergen extract can contribute to risk of allergic disease CRD: Test for IgE sensitisation against individual protein within whole allergen extract Diagnostic use * Food allergy (nuts, egg, milk) * Insect allergy (wasp and bees) * Guide to immunotherapy (grass and HDM)

Answer 11

Storage proteins (2s albumins) - severe reactions pathogenesis related proteins - (PR10 bet v1 homologue) which are also found in tree pollens, fruits and vegetables (ie cross-react with these things): mild reaction Non specific lipid transfer proteins, also found in in fruit (peach) , tree pollen (plane), vegetables and legumes ( can be mild or severe)

Answer 12

Omega-5-gliadin better marker of specific wheat allergy than total wheat IgE

Answer 13

Heat stable proteins ovomucoid (egg) and caseins ( estimate who outgrows allergy)

Answer 14

Parvalbumin in fish, Tropomyosin in crustaceans (cross reactive)

Answer 15

No access to SPT and/or IDT - ie GP can’t stop anti-histamines history of dermatographism, extensive eczema history of anaphylaxis – because wouldn’t want to do skin prick Decision on who needs food challenge Prediction for resolution of egg, milk, wheat allergy monitor response to anti-IgE therapy

Answer 16

concentration - higher more likely = sx molecular target (within whole extract or even individual epitope) can be linked to sx affinity to target - higher associated with risk - dont measure affinity Capacity of IgE antibody to induce mast/basophil degranulation

Answer 17

it is a **biomarker for anaphylaxis** tryptase is a pre-formed protein **found in mast cell granules** **systemic degranulation of mast cells -> increase in tryptase** peak at 30min - 2hrs return to baseline by 6-12hrs - need serial measures Failure to return to baseline after anaphylaxis may be indicative of systemic mastocytosis and hereditary alpha tryptasaemia useful if anaphylaxis dx not clear reduced sensitivity for food induced anaphylaxis because mucosal immune response (rather than drug/venum that effect endothelial cells)

Answer 18

**measure basophil response to IgE cross linking** **Activated basophils increase the expression of CD63, CD203, CD300 protein on cell surface** used in dx of food and drug allergy - surrogate marker for challenge test Efforts to standardise test to use by diagnostic laboratories to reduce need for challenge tests problem is some of the population have basophils that are refractory to responding to ag

Answer 19

gold standard ingest increasing volumes of the allergen either double blind placebo/open challenge close medical supervision - very expensive in terms of clinician time difficult to interpret mild sx risk of severe rn

Answer 20

Acute onset of symptoms and/or signs (minutes to 4-6 hours) Severe/life threatening ABC problems Skin and mucosal symptoms and signs (can be absent 10-20% of cases)

Answer 21

Skin (hives, itch, swollen lips, tongue, uvula) (84%), Cardiovascular compromise (collapse, syncope, incontinence symptoms, drop in BP) (72%) Respiratory compromise (SOB, wheeze, stridor, fall in PEF, hypoxemia in 68%. resp more in children adults - CVS

Answer 22

Incidence: 1.5-8/100,000 persons years incidence is increasing prevalence 0.3-5.1% more common aged 0-4yrs children - food adult - drug and venum idiopathic in 20-30% of cases - shrimp, wheat, red meat

Answer 23

Distinction doesn’t matter for treatment but might change Ix IgE and complement - more associated with monoclonal ab infusion related reactions

Answer 24

SKIN: Chronic urticaria and angioedema (ACE inhibitors) THROAT SWELLING: C1 inhibitor deficiency CARDIOVASCULAR: Myocardial infarction and PE RESPIRATORY: Very severe asthma, vocal cord dysfunction, inhaled FB NEUROPSYCHIATRIC: Anxiety or panic disorder ENDOCRINE: carcinoid and phaechromocytoma TOXIC: Scromboid toxicity (Histamine poisoning ) IMMUNE: Systemic mastocytosis

Answer 25

**serial tryptase mx - 30min-2hr, then at 24hr ** Concentration greater then (1.2 x baseline tryptase) + 2ug/L support a diagnosis of anaphylaxis. it is retrospective dx -ve doesnt rule out anaphylaxis - esp if food and have mucosal sx

Answer 26

α1 receptors: causes peripheral vasoconstriction, reverses low BP and mucosal oedema β1 receptor: increases heart rate and contractility and BP β2 receptor: relaxation of bronchial smooth muscle and reduces release of inflammatory mediators from mast cells/basophils

Answer 27

supine raise legs IM adrenaline - if no response -> repeat and administer IV crystalloid fluids *anti-histamine after ABC corrected*

Answer 28

if no improvement in ABC (no improvement after 2 IM adrenaline) :

Answer 29

refer - allergy clinic ix cause give info on - sx recognition, avoidance of triggers, epipen prescription of emeergency anaphylaxis kit Copy of management plan and training for patient, carers, school staff and GP venum immunotherapy and drug desensitisation as appropriate if food - refer to dietician medic alert bracelet utilise support groups

Answer 30

adverse health effect arising from specific immune response that occurs reproducibly on exposure to a given food

Answer 31

non immune reactions which include metabolic, pharmacological and unknown mechanisms eg * Food poisoning (bacterial, scromboid toxin) * Enzyme deficiencies (lactase) * Pharmacological (caffeine, tyramine )

Answer 32

fads eating disorders

Answer 33

IgE mediated reactions (anaphylaxis, OAS) Mixed IgE and cell mediated (atopic dermatitis) Non IgE mediated (coeliac disease – type 4 hypersensitivity) Cell mediated (contact dermatitis)

Answer 34

milk and egg yes rarely peanut and treenut

Answer 35

an important risk factor for food allergy (indication for allergy testing even in absence of clinical history)

Answer 36

what does pt mean by allergy Is it IgE or not determine dose of allergen, how prepared, co-factors - all alter sx hx of atopy previous ix elimination of food make a difference ddx - intolerance, eating disorder, coeliac disease

Answer 37

what does pt mean by allergy Is it IgE or not determine dose of allergen, how prepared, co-factors - all alter sx hx of atopy previous ix elimination of food make a difference ddx - intolerance, eating disorder, coeliac disease

Answer 38

hx SPT/IgE blood test - if -ve basically excludes IgE mediated allergy monitor results over time - for persistance or resolution Fruit and vegetable skin prick test solutions are labile and it often better to useful use actual fruit or vegetable. Testing for individual allergen protein component can distinguish between IgE sensitisation and IgE mediated allergy gold standard is double blind oral food challenge

Answer 39

avoidance * education - labels, restaurants, school * nutritional input * mental health support emergency * anaphylaxis mx * ensure allergic asthma is well controlled

Answer 40

breast feeding early introduction of peanut

Answer 41

**anaphylaxis** - Peanut, tree nut, shellfish, fish, milk and eggs are most common **food associated exercise induced anaphylaxis** - food -> anaphylaxis if exercise within 4-6hr of ingestion - wheat, shellfish, celery **Delayed food-induced anaphylaxis to beef, pork, lamb** **oral allergy syndrome**

Answer 42

sx 3-6hr after red meat and gelatin IgE antibody to oligosaccharide alpha-gal (α1, 3-galactose) found in gut bacteria Induced by tick bites: * Human make ab to alpha-gal * Human eat meatr with alpha-gal – Ig E

Answer 43

Limited to oral cavity, swelling and itch: only 1-2% cases progresses to anaphylaxis Sensitisation to inhalant pollen protein -> cross reactive IgE to food Onset after pollen allergy established: affect adults > young children Respiratory exposure to pollen (birch) -> IgE directed to homologous proteins in stone fruits (apple, pear) vegetables (carrot) and nuts (peanut, hazelnut) Cooked fruits, vegetables and nut cause no symptoms: heat labile allergens detected by component allergen tests