resp hypersensitivity Flashcards

1
Q

what is type I hypersensitivity

A

immediate

IgE mediated antibody response to external antigen

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2
Q

what are some examples of T1H

A

allergy
asthma
parasite e.g. schistosomiasis

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3
Q

what cells of the adaptive immune system are involved in T1H

A

Th2 - (CD4, HLA class II)
B cells
IgE

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4
Q

what cells of the innate immune system are involved in T1H

A

eosinophils

mast cells

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5
Q

what is the management of T1H

A
mast cell stabilisers
antihistamines
leukotriene antagonists
corticosteroids
immunotherapy
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6
Q

how is T1H diagnosed

A

skin prick test
quantitative specific IgE to positive allergen
challenge test

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7
Q

what IL produced by Th2 cells activates

1) eosinophils
2) mast cells
3) IgE plasma cells

A

1) IL5
2) IL4 and IL13
3) IL4, IL5 and IL13

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8
Q

what happens in 1st encounter with allergen in T1H

A

B cells produce antigen specific IgE antibody and allergen is cleared
remaining IgE bind to Fc receptors on mast cells

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9
Q

what happens in 2nd encounter with allergen in T1H

A

allergen binds to IgE coating mast cells and disrupts membrane causing release of inflammatory molecules —> degranulation

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10
Q

what does T2H involve

A

direct cell killing - bound antigen on surface

localised

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11
Q

what cells of the adaptive immune system does T2H involve

A

IgM , IgG

B cells

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12
Q

what cells of the innate immune system does T2H involve

A

complement

phagocytes

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13
Q

give examples of T2H

A

immune haemolytic anaemias

  • ABO blood transfusion reactions
  • drug induced haemolysis

acute vascular rejection
Good pasteurs syndrome

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14
Q

what is the treatment of T2H

A

immunosuppression

plasmapheresis

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15
Q

what happens in T2H

A

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”

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16
Q

what is T3H

A

immune Complex mediated
antibody to soluble antigens
systemic

17
Q

what are some examples of T3H

A

acute hypersensitivity pneumonitis
SLE
rheumatoid arthritis

18
Q

what cells of the adaptive immune system are involved in T3H

A

B cells

IgG

19
Q

what cells of the innate immune system are involved in T3H

A

complement

neutrophils

20
Q

what happens in T3H

A

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
21
Q

what is the management of T3H

A

avoidance
corticosteroid
immunosuppression

22
Q

what is T4H

A

Delayed type

23
Q

what cells are involved in T4H

A
Th1 cells (Adaptive)
macrophages (innate)
24
Q

what are some examples of T4H

A
sarcoidosis
leprosy
Hep B
contact dermatitis
TB
T1 diabetes
Psoriasis
cellular rejection of organ transplant
25
Q

what forms in T4H

A

granuloma

26
Q

what happens initially in T4H

A

initial sensitisation to antigen generates primed Th1 cells and memory cells

27
Q

what does subsequent exposure in T4H cause

A

activates previously primed Th1 cells

  • recruitment of macrophages, lymphocytes, neutrophils
  • release of proteolytic enzymes
28
Q

what is the role of IFN- Y in T4H

A

activates macrophages increasing the release of inflammatory markers

29
Q

what is the role of IFN-a in T4H

A

local tissue destruction

30
Q

what is the treatment of acute sarcoidosis

A

NSAIDs

31
Q

what is the management of sarcoidosis

A

corticosteroids

32
Q

what kind of hypersensitivity is graves

A

type 2