respiratory_week_5_20190518190157 Flashcards
what is an allergy
IgE mediated antibody response to external antigen (allergen)
what is the role of T lymphocytes in allergy
TH2 cells provide help for B cells to make IgE antibody
what is the role of mast cells in allergy
produce vasoactive substances (histamine typtase, heparin, leukotrienes, prostaglandin, IL-4 and TNFalpha)also express receptors for Fc region of IgE on surface
residual IgE antibodies bind to circulating mast cells via Fc receptor with no great consequence until re-encounter with allergen - what happens
allergen binds to IgE coated mast cells which causes release of vasoactive mediators as well as increased cytokines and leukotriene transcription
what symptoms occur within minutes of release of vasoactive mediators
urticaria (hives, rash, blisters)angiodema (swelling)asthma allergic rhinitis, conjunctivitis anaphylaxis
how to block mast cell activation (management)
mast cell stabilisers (sodium cromoglycate)
how to prevent effects of mast cell activation (management)
antihistamines (H1 receptor antagonists) or leukotriene receptor antagonists (montelukast)
use of anti-inflammatory agents in management
corticosteroids - inhibit formation of inflammatory mediators (platelet activating factor, prostaglandins and cytokines)
how to treat anaphylaxis
self injectable adrenaline - acts on B2 adrenergic receptors to constrict arterial smooth muscle - increases BP and dilates bronchial SM (decreasing airflow obstruction)
how does immunotherapy work
subcutaneous injection of tiny amounts of allergen, gradual increase in dose, immune deviation and this may lead to inhibition of anaphylaxis
what is the onset of type 1 - immediate hypersensitivity (allergy)
seconds (if IgE performed)
what is infectious trigger of type 1
parasites (e.g. schistosomiasis)
what is the environmental trigger of type 1
allergens e.g. dust mite, animal dander, pollen, peanut
what is the adaptive immune mediators of type 1
TH2 cells, B cells, IgE
what is the innate immune mediators of type 1
mast cells, eosinophils
what is onset of type 2 (bound antigen)
seconds (if IgG or IgM is performed)
what is environmental trigger of type 2
immune haemolytic anaemias
what is autoimmune conditions of type 2
graves disease (hyperthyroidism) and good pastures syndrome (bleeding in lungs and kidneys - causes glomerulonephritis and pulmonary haemorrhage)
what is adaptive immune mediators of type 2
B cells, IgG / IgM
what is innate immune mediators of type 2
complement, phagocytes
what is onset of type 3 (immune complex)
hours (if IgG performed)
what is infectious trigger of type 3
post-streptococcal glomerulonephritis
what is environmental trigger of type 3
farmers lung
what is immune conditions of type 3
SLE (lupus) - auto antibodies against nuclear antigens, increase risk of CVDmanagement: limit sun, hydroxychloroquine, corticosteroids, immunosuppressive agents or inhibit B cell proliferation