resp hypersensitivity Flashcards
what is type I hypersensitivity
immediate
IgE mediated antibody response to external antigen
what are some examples of T1H
allergy
asthma
parasite e.g. schistosomiasis
what cells of the adaptive immune system are involved in T1H
Th2 - (CD4, HLA class II)
B cells
IgE
what cells of the innate immune system are involved in T1H
eosinophils
mast cells
what is the management of T1H
mast cell stabilisers antihistamines leukotriene antagonists corticosteroids immunotherapy
how is T1H diagnosed
skin prick test
quantitative specific IgE to positive allergen
challenge test
what IL produced by Th2 cells activates
1) eosinophils
2) mast cells
3) IgE plasma cells
1) IL5
2) IL4 and IL13
3) IL4, IL5 and IL13
what happens in 1st encounter with allergen in T1H
B cells produce antigen specific IgE antibody and allergen is cleared
remaining IgE bind to Fc receptors on mast cells
what happens in 2nd encounter with allergen in T1H
allergen binds to IgE coating mast cells and disrupts membrane causing release of inflammatory molecules —> degranulation
what does T2H involve
direct cell killing - bound antigen on surface
localised
what cells of the adaptive immune system does T2H involve
IgM , IgG
B cells
what cells of the innate immune system does T2H involve
complement
phagocytes
give examples of T2H
immune haemolytic anaemias
- ABO blood transfusion reactions
- drug induced haemolysis
acute vascular rejection
Good pasteurs syndrome
what is the treatment of T2H
immunosuppression
plasmapheresis
what happens in T2H
antibody binds to cell surface antigen
- activation of complement
- mediated by B cells/IgG/IgM —> NK cells and eosinophils activated —> antibody acts as opsonin for phagocytes —> phagocytosis of antigen +ve cells
“antibody mediated phagocytosis”
what is T3H
immune Complex mediated
antibody to soluble antigens
systemic
what are some examples of T3H
acute hypersensitivity pneumonitis
SLE
rheumatoid arthritis
what cells of the adaptive immune system are involved in T3H
B cells
IgG
what cells of the innate immune system are involved in T3H
complement
neutrophils
what happens in T3H
excess antigen present - antibody binds and forms small immune complexes
- deposit in BV wall
- activates complement
- infiltration of macrophages and neutrophils
- enzymes released from neutrophils cause damage to endothelial cells of basement membrane
what is the management of T3H
avoidance
corticosteroid
immunosuppression
what is T4H
Delayed type
what cells are involved in T4H
Th1 cells (Adaptive) macrophages (innate)
what are some examples of T4H
sarcoidosis leprosy Hep B contact dermatitis TB T1 diabetes Psoriasis cellular rejection of organ transplant
what forms in T4H
granuloma
what happens initially in T4H
initial sensitisation to antigen generates primed Th1 cells and memory cells
what does subsequent exposure in T4H cause
activates previously primed Th1 cells
- recruitment of macrophages, lymphocytes, neutrophils
- release of proteolytic enzymes
what is the role of IFN- Y in T4H
activates macrophages increasing the release of inflammatory markers
what is the role of IFN-a in T4H
local tissue destruction
what is the treatment of acute sarcoidosis
NSAIDs
what is the management of sarcoidosis
corticosteroids
what kind of hypersensitivity is graves
type 2
