Allergy, hypersentivity and intolerance Flashcards
what are the types
type I-iv
what is type I mediated by
Ig-E- immediate
what is type ii mediated by
Ig-G- cytotoxic
what is type iii mediated by
Ag-Ab complex
what is type iv mediated by
cell mediated- delayed
what is atopy
production IgE against common environmental allergens
what is the response to allergen being processed in atopy
TH2-> IL-4,5 -> IgE and development of mast cells and eosinophils
where can you find mast cells
on major surfaces
what mediators are released by mast cells
histamine, lipids, cytokines, proteases, proteoglycans
action of the mediators released by mast cells
vasodilation, increase capillary permeability, smooth muscle constriction in airways and dilation in blood vessels
what is the difference between extrinsic and intrinsic asthma
extrinsic- triggered by certain allergens. intrinsic- no allergens identified
precipitating factors
perennial (house dust mite, feathers, pets); seasonal (tree, pollen); non specific (cold, exercise)
diagnosis asthma
reversible so increase by 15% after bronchodilator (FEV1)
how can you identify allergens in asthma
skin prick or blood- RAST, FEIA
how is the response in extrinsic asthma
biphasic- immediate (<30 mins), delayed (6-8hours)
how to treat asthma
B agonists, steroids, theophyllines
what is blocked in rhinitis/ conjunctivitis
sinus Ostia/ Eustachian tube
what is anaphylaxis
systemic mastcell and basophil activation leading to cardio-respiratory collapse
what is the term for IgE activated ana
anaphylaxis
what is the term for non IgE activated ana
anaphylactoid
signs in anaphylaxis
flushing, urticaria, abdo pain, wheeze, angioedema, stridor, cyanosis, decr bp, arrest
what blood can be used to confirm anaphylaxis
incr serum tryptase
treatment anaphylaxis
lie flat, legs in air; adrenaline IM 0.6mg; O2 and bronchodilator; IV chlorphenamine and hydrocortisone; IV fluids; cardio-resp support
what is desensitisation therapy
infection of allergen to induce tolerance for 3-5 years
