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42 Cards in this Set
- Front
- Back
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Hypersensitivity definition |
reactions of immune system detrimental to health double edged sword because: response to pathogen is appropriate but hypersensitivity reaction → detrimental effects to host |
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allergen |
not pathogen antigens but innocuous substances' pathogesn e.g. pollen, animal proteins (egg) |
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Type I reaction |
IgE mediated mast cell degranulation e.g. allergy to: food, drug, venom, hay fever |
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Type II reaction |
IgG autoantibody e.g. Myasthenia graves, ITP, Goodpasture's Goodpasture's = glomerulonephritis + alveolar haemorrhage NB Type II + III are known as autoimmune conditions |
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Type III reaction |
IgG/Antigen immune complex damage
e.g. SLE, mixed cyroglobulinaemia NB Type II + III are known as autoimmune conditions |
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Type IV |
T cell mediated e.g. contact dermatitis, DTH, Mantous test (for TB) |
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Type II + III reaction are... |
Autoimmune conditions |
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Allergy refers to Type ___ Ig___ mediated reactions |
Allergy refers to Type I IgE mediated reactions |
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Type I time period? seriousness? Ab... |
immediate, within minutes life threatening Ig£ skin/serum testing can be done |
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Type IV time period? seriousness? Ab... |
>4 hours difficult to find the allergen patch testing |
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IgE class switching |
IgE switching Th 2 produced IL4 + IL13 are needed IgE switching inhibited by IFNgamma |
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sometimes get allergic response when substance is presented in ___________ way |
sometimes get allergic response when substance is presented in unusual way |
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long term memory |
long term memory against allergen so can be removed quickly long term memory comes from class switched IgE Ab patient is sensitised to allergen |
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reexposure after long term memory has been made |
patient may have IgE response IgE against various allergens safely have contact with them |
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allergy testing |
cannot be used as screening test should only be for strong clinical + temporal history |
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genetic factors for allergy |
genetic factors predispose to IgE response to antigen e.g. polymorphism of FcepsilonRI i.e. (the receptor for IL4) ↑ risk of conditions e.g. asthma, dermatitis, rhinitis |
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atopic patients |
those who have polymorphism of FcepsilonRI i.e. (the receptor for IL4) |
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hygiene hypothesis |
exposure to pathogen early in life → protection from atopic disease e.g. asthma etc. |
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Type 1/IgE mediated allergic reaction n |
1. Exposure + sensitisation 2. Antigen binds specific IgE 3. Cross links FcεRI 4. release of pre-formed mediators 5. ↑ synthesis of late mediators |
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Mast cell mediators preformed mediators list... late phase mediators... |
preformed mediators: histamine, kallikrein → activate bradykinin, serotonin, proteases, heparin late phase mediators: prostaglandins leukotrienes cytokines |
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histamine action |
↑ vascular permeability irritates nerve endings → pain |
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kallikrein action |
activates bradykinin bradykinin is a vasodilator |
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Serotonin action |
smooth muscle contraction
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Heparin action |
anti-coagulant
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late phase mediator actions? |
lots of action perpetuate + escalate immune response particular cellular recruitment |
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Anaphylaxis definition |
severe life threatening
systemic hypersensitivity reaciton life threatening airway and/or breathing and/or circulation problems associated with skin + mucosal changes |
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causes of anaphylaxis |
drugs insect bites allergies no cause - idiopathic anaphylaxis |
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Effects of anaphylaxis: list of body systems affected |
systems affected: airway breathing circulation -hypotension -tachycardia -cardiac arrest neurological skin changes GI |
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Effects of anaphylaxis : airway physiological reaction... sign... action of adrenaline... |
↑ vascular permeability → laryngeal oedema + tongue swelling action of adrenaline → ↓ vascular permeability |
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Effects of anaphylaxis : breathing physiological reaction... sign... action of adrenaline... |
smooth muscle contraction n → bronchospasm action of adrenaline → smooth muscle dialtion |
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Effects of anaphylaxis : circulation - hypotension physiological reaction... sign... action of adrenaline... |
vasodilation → faint + collapse action of adrenaline → vasoconstriction |
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Effects of anaphylaxis : circulation - tachycardia physiological reaction... sign... action of adrenaline... |
↓ vascular resistance → ↑ HR action of adrenaline → ↑ vascular resistance |
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Effects of anaphylaxis : circulation - cardiac arrest physiological reaction... sign... action of adrenaline... |
↓ coronary blood flow → cardiac arrest action of adrenaline → ↑ coronary blood flow |
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Effects of anaphylaxis : neurological physiological reaction... sign... action of adrenaline... |
↓ cerebral blood flow → confusion action of adrenaline → ↑ cerebral blood flow |
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Effects of anaphylaxis : skin changes physiological reaction... sign... |
histamine + bradykinin release → urticaria |
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Effects of anaphylaxis : GI symptoms physiological reaction... sign... action of adrenaline... |
↑ smooth muscle contraction
→ diarrhoea, vomiting, incontinence
action of adrenaline → smooth muscle dilatation |
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Rx for Anaphylaxis Rx for mild allergic reactions |
Adrenaline → intramuscularly given for mild allergic reactions: Antihistamines Steroids |
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Adrenaline dose |
0.3mg for adults 0.15mg for children |
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IV Adrenaline |
given under cardiac surveillance |
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Anti-helminth immunity |
parasites too big for phagocytosis
IgE mediated removal Eosinophils fight infection, ↑ in parasite iL-5 (made by mast cells) → mobilise eosinophil from bone marrow + attracts them to the helminth eosinophils attach to parasite by receptors for both IgG + IgE |
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Anti helminth immunity Eosinophils role |
FcεRI → release of eosinophil lysosomal granules into parasite surface MBP (major basic protein) alkaline, major eosinophilic mediator, toxic to helminth Eosinophils can → ROS + Nitrogen radicals Helminth is cleared by IL-13, which → goblet cell hyperplasia, mucus production → contraction of gut muscle → elimination of the parasite |
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Eosinophil damage |
release of eosinophil chemotactic factor → damage e.g. lung damage in asthma |
