hypersensitivity Flashcards by Rosa Bock

type 1 hypersensitivity reaction

allergic - immediate

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what is the definition of allergy

IgE mediated antibody response to an external antigen

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what is the hypothesis for the reason of inc prevalence of allergy

hygiene hypothesis

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where do mast cells reside

tissues

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what preformed substances do mast cells produce

histamine, tryptase and heparin

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what substances do mast cells synthesise on demand

Leukotrienes, prostaglandins, cytokines including IL4 and TNF

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what effect do mast cells have

inflammatory cascade

inc blood flow
SM contraction
inc vascular permeability
inc secretions at mucosal surface

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what are the functions of mast cells

important in defence against parasites, and wound healing

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what receptors do mast cells express

Fc receptor

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what is extrinsic asthma

response to external antigen

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what is extrinsic asthma mediated by

IgE

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what is the clinical manifestation of bronchoconstriction

wheeze

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what is the clinical manifestation of mucosal oedema and inc secretion

sputum production

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why is sputum often yellow

Infiltration of lymphocytes and eosinophils into bronchioles

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what are some other names for urticaria

hives
nettle rash
blisters

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what is angioedema

Self-limited, localised swelling of subcutaneous tissues or mucous membranes

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is angioedema pitting oedema

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CF of anaphlaxis

sense of impending doom 
hypotension 
urticaria 
itch
diarrhoea and abdo pain 
arrhythmia 
flush and sweat

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can mast cells degranulate spontaneously

yes

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what can u get urticaria in response to

pressure or heat

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what drugs can cause mast cell degranulation

morphine and other opiates

aspirin and NSAIDs

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what is samters triad

asthma, nasal polyps and salicylate sensitivity

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what is aspirin induced asthma treated with

CysLt receptor antagonists

eg montelukast

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what is aspirin indued asthma triggered by

aspirin and also other classical NSIDs (diclofenac and ibuprofen)

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how would you test for anaphylaxis

evidence of mast cell degranulation - serum tryptase

what is the gold standard test for support a allergy diagnosis

skin prick test

what should be stopped 48 hours before a skinprick test

antihistamines

what other allergy investigations are available

specific IgE test and challenge test

specific IgE test

measure amount of IgE in serum against specific allergen

is total IgE useful in the diagnosis of allergic disease

in anaphylaxis what is the rise in tryptase proportional to

the drop in BP

what is sodium cromoglycate

a mast cell stabiliser

how is sodium cromoglycate used

topical spray

who is sodium cromoglycate used in

kids especially

what is symbicort

budesonide and formoterol

what is serotide

fluticasone and salmeterol

what is anaphylaxis managed with

self injectable adrenaline

what effect does adrenaline have

act on B2 ADR to constrict arterial SM - inc BP there by limiting vascular leakage - dilates bronchial SM thereby dec airflow obstruction

what is immunotherapy

controlled exposure to inc amounts of allergen

what are type II hypersensitivity reactions

direct cell killing

type II hypersensitivity

antibody binds to cell surface antigen activating complement and causing opsonisation

type II hypersensitivity - what do B cells produce

IgM or IgG antibody against membrane protein - bind to cell surface antigen

what is involved in the classical complement pathway

CI 2 and 4

what is the main complement pathway thing

what does C3 activate

MAC

what can MAC do

direct killing of encapsulated bacteria by punching holes in bacterial cell membranes

what does C3 do - 3 things

chemotaxis solubilisation of immune complexes opsonisation

chemotaxis

inc vascular permeability inc the traffic of ells to the site of infection

what do opsonins act as

bridge between pathogen and receptor

what can complement fragments act as

opsonins - C3b

what is an example of type II hypersensitivity

transfusion ABO reaction

what is immediate haemolytic transfusion reaction

overwhelming systemic inflammatory response

what is autoimmune haemolytic anaemia

antibodies bind to red cells

what is Idiopathic thrombocytopaenic purpura

antibodies bind to platelets

what is goodpastures syndrome

antibodies bind to glomerular basement membrane

what is myasthenia gravis

antibodies bind to ACh receptor

what is guillan barré

antibodies bind to perisperhal nerve glycoprotein

what is graves disease

antibodies bind o TSH receptor

what is pemphigus vulgaris

antibodies bind to epithelial cell cement

what diseases may be transferred to neonate

myasthenia gravis, idiopathic thrombocytopaenic purpura, Rhesus disease

how do u manage type II hypersensitivity reactions

plasmapheresis - removal of pathogenic antibody

what is type III hypersensitivity reaction

immune complex mediated

type III hypersensitivity reaction

generalised reaction resulting from immune complex deposition in blood vessel walls, skin joints and glomeruli where they cause a chronic inflammatory response

III hypersensitivity reaction example

farmers lung

what are the agents of farmers lung

Aspergillus fumigatus | Micropolyspora faeni

what are the agents in bird fanciers lung

Avian serum proteins

what are the agents in malt workers lung

aspergillus clavatus

what are the agents in cheese workers lung

Aseprgillus clavatus | Penicillum casei

what are the agents in maple bark strippers lung

Cryptostroma corticale

what causes breathlessness in hypersensitivity pneumonitis

Alveolitis, caused by activated phagocytes and complement – results in decreased efficiency of gas transfer

what is SLE

antibodies produced against the contents of cell nuclei, form immune complexes which are deposited etc

what does complex deposition in joints result in

arthralgia

what does deposition of IgG immune complexes in glomeruli cause

renal dysfunction

what does immune complex in skin cause

vasculitic purpura

how do u diagnose type III reactions

specific IgG to putative antigen

how does one manage type III reactions

dec inflammation - corticosteroids dec antibody production - IS

type IV

delayed

what cell mediates type IV

T cell

what is the pathophysiology of type IV

initial sensitisation to antigen primes the T cells subsequent exposure activates the primed T cells which recruit other cells and release enzymes

an example of type IV

nickel hypersensitivity

non autoimmune type IV diseases

TB, sarcoidosis, leprosy, cellular rejection of solid organ transplant

autoimmune type IV diseases

diabetes, psoriasis, rheumatoid arthritis

what is a granuloma

organised collection of activated macrophages and lymphocytes

hypersensitivity Flashcards

(83 cards)