Hypersensitivity Reactions

Question 1

define hypersensitivity reactions

Answer 1

an antigen specific reaction that is either inappropriate or excessive causing harm to the host

Question 2

what are the 2 phases in hypersensitivity reactions

Answer 2

1. sensitisation phase

2. effector phase

Question 3

what are type 2 hypersensitivity reactions

Answer 3

where antibodies are produced against cell membrane bound antigens

Question 4

what are the effects of type 2 reactions

Answer 4

tissue damage and physiological changes

Question 5

how does tissue damage occur in type 2 reactions

Answer 5

complement cascade - causes neutrophil recruitment, cell lysis and opsonisation
antibody dependant cell cytotoxicity

Question 6

what is antibody dependant cell cytotoxicity

Answer 6

where natural killer cells binds to the antibodies and release toxic radicals into the cells

Question 7

what are type 3 hypersensitivity reactions

Answer 7

where the production of immune complexes cause problems due to their deposition in tissues

Question 8

true or false: membrane bound antigens are targeted in type 3 reactions

Answer 8

false- it is soluble antigens

Question 9

what antibodies are involved in type 3 reactions

Answer 9

IgG and IgM

Question 10

what are type 4 reactions

Answer 10

where lymphocytes and macrophages are involved in the reaction

Question 11

true or false: type 4 reactions are immediate

Answer 11

false - they are delayed

Question 12

what are the treatments for type 2 reactions

Answer 12

immune suppressants - so that you can’t produce the antibodies
plasmapheresis
splenectomy
receptor stimulators/blockers

Question 13

what is plasmapheresis

Answer 13

the cleaning of plasma to remove the antigen from blood

Question 14

what is the treatment for type 3 and 4

Answer 14

non steroidals, corticosteroids and monoclonal antibodies

Question 15

what type of reaction is involved in Rheumatoid arthritis

Answer 15

type 3

Question 16

what type of reaction is systemic lupus erthematosus

Answer 16

type 3 - antibody is against Ds-DNA

Question 17

what type of reaction is glomerulonephritis

Answer 17

type 3 - there is sustained presence of a microbe causing the production of lots of immune complexes

Question 18

what type of reaction occurs when you transfuse the wrong blood type

Answer 18

type 2

Question 19

why does a hypersensitivity reaction occur after giving a group blood type

Answer 19

you have naturally occurring antibodies against the other blood types which will destroy foreign RBCs

Question 20

what type of antibody is involved in blood transfusion reactions

Answer 20

IgM

Question 21

why can a mother have a child with a different blood type but not have her antibodies attack the Childs RBCs

Answer 21

as the antibodies are IgM,so can’t cross the placenta

Question 22

what is haemolytic disease of the newborn

Answer 22

when a RH D antigen positive child is being carried in a negative mother. when there blood mixes the mother produces antibodies against the Rh D antigen which attack the Childs RBCs

Question 23

why can the mothers antibodies against the Rh Antigen reach the child

Answer 23

they are IgG so can cross the placenta

Question 24

what is myasthenia gravis

Answer 24

where you produce antibodies against the ACh receptors, meaning nervous conductance can’t occur very well

Question 25

what type of hypersensitivity reaction occurs in myasthenia gravis

Answer 25

type 2

Question 26

what are the 3 sub types of type 4 reactions

Answer 26

1. contact 2. tuberculin 3. granulomatous

Question 27

what is contact hypersensitivity

Answer 27

where the antigen binding to the hosts epidermal proteins can cause a reaction

Question 28

what is tuberculin hypersensitivity

Answer 28

where the TB microbe cannot be removed so granulomas form around it

Question 29

what is the Mantoux test

Answer 29

injecting a small bit of TB into the skin to see if there is a TH1 response - if there is a small dot it shows the person has already been sensitised

Question 30

what type of hypersensitivity disease is hashimotos

Answer 30

type 4 and type 2 - as antibodies are produced but there is also a TH1 response

Question 31

true or false: type 1reactions have a delayed response

Answer 31

false - the response is immediate

Question 32

what happens during a type 1 reaction

Answer 32

a TH2 response is initiated to produce IgE (instead of the normal TH1 response)

Question 33

what does the IgE in type 1 reactions do

Answer 33

activates mast cells

Question 34

where are mast cells usually found

Answer 34

in the skin, GI tract, respiratory tract

Question 35

name some of the mediators released from the mast cell granules

Answer 35

histamine, leukotriene, platelet activating factor, tryptase

Question 36

what does histamine do

Answer 36

increases vascular permeability, smooth muscle contraction

Question 37

what do leukotrienes do

Answer 37

smooth muscle contractions, mucus secretions

Question 38

describe the sensitisation phase of type 1 reactions

Answer 38

upon exposer IgE is produced which waits on the mast cells

Question 39

describe the effector phase of type 1 reactions

Answer 39

the antigen causes cross linkage of 2 IgE antibodies, activating the mast cell which they are on

Question 40

what is urticaria

Answer 40

skin rash

Question 41

what is angioedema

Answer 41

swelling in the eyes, lips and mouth due to involvement of vasculature

Question 42

what are the treatment options for type 1 reactions

Answer 42

allergen desensitisation anti-IgE monoclonal antibody anti-histamine leukotriene receptor antagonist