hypersensitivity

Question 1

what is hypersensitivity?

Answer 1

state of altered reactivity in which the body reacts with an exaggerated immune response to a foreign agent

Question 2

what is the difference between an allergy and an intolerance?

Answer 2

allergy causes an immune reaction, intolerances don’t

Question 3

what does atopic mean ?

Answer 3

genetic disposition to an allergy

Question 4

which type of hypersensitivity is an allergy?

Answer 4

type 1

Question 5

type 1 hypersensitivity is mediated by what?

Answer 5

IgE

Question 6

what is type 1 hypersensitivity?

Answer 6

allergic reaction provoked by reexposure to a specific type of antigen referred to as an allergen

Question 7

which hypersensitivity is most common?

Answer 7

type 1

Question 8

immediate hypersensitivity refers to which type?

Answer 8

type 1

Question 9

atopy is associated with which typeof hypersensitivity?

Answer 9

type 1

Question 10

type 1 hypersensitivity may cause what in extreme cases?

Answer 10

anaphylaxis

Question 11

what is anaphylaxis?

Answer 11

acute serious allergic response

Question 12

IgE is bound to 2 immune cells that allow it to cross link to antigens, what are these 2 cells?

Answer 12

mast cells and basophils

Question 13

what is a hapten?

Answer 13

an organic molecule attached to a carrier protein which elicits an immunological reaction

Question 14

some drugs may act as haptens, give an example of a drug and how it works?

Answer 14

penicillin - induce antibody mediated allergic reaction

Question 15

the immune response in allergy begins with sensitisation, what happens to IgE during sensitisation?

Answer 15

• IgE producing B cells are activated after 1st exposure to allergen
• IgE binds to Fc receptor on mast cell or CD63 receptor on basophil

Question 16

after sensitisation, elicitation takes place, what happens to IgE during this process?

Answer 16

• IgE recognises allergen and next exposure binds rapidly causing immediate degranulation

Question 17

the priming of IgE to respond to an antigen is known as?

Answer 17

sensitisation

Question 18

the storms cause by IgE are a result of what?

Answer 18

elicitation

Question 19

mast cell degranulation releases what?

Answer 19

histamine, proteases, antimicrobial peptides

Question 20

what is cutaneous atopy?

Answer 20

wheal and flare

Question 21

what is urticaria?

Answer 21

itchy rash

Question 22

what is allergic rhinitis?

Answer 22

hay fever

Question 23

what is atopic dermatitis?

Answer 23

allergic eczema

Question 24

what happens during anaphylactic shock?

Answer 24

mast cells degranulate all over the body

Question 25

name 3 potentially fatal reactions that may occur as a result of anaphylactic shock and how they may cause death?

Answer 25

- laryngeal oedema (suffocation) - bronchiole constriction (suffocation) - peripheral oedema (fluid loss from BV causing hypertension and heart attack)

Question 26

can can allergy be tested?

Answer 26

- skin prick test (prick with suspected allergen) - blood test (measure IgE in response to allergen) - patch test (allergen added to metal discs taped to skin) - food challenge (in ITU setting)

Question 27

what is the treatment for allergy?

Answer 27

- avoid allergen - drugs - immunological treatment

Question 28

what drugs are used for allergy and how do they work?

Answer 28

anti histamine - compete with histamine for receptors hydrocortisone - block histamine synthesis cromoglycate - stabilise mast cells, stop histamine release epinephrine - immediate treatment for anaphylactic shock

Question 29

what immunological therapy is available for allergy treatment and how does it work?

Answer 29

hyposensitisation - repeat injection of allergen | - shift IgE to IgG

Question 30

what type of drugs are antihistamines?

Answer 30

inverse agonists - inactivate receptors

Question 31

what effect does epinephrine have on patients?

Answer 31

- bronchodilation | - reduce inflammatory mediators

Question 32

what is type 2 hypersensitivity?

Answer 32

action of complement by IgG or IgM binding to antigenic cell, causing cell lysis

Question 33

give an example of type 2 hypersensitivity?

Answer 33

blood transfusion

Question 34

how does cell lysis occur during type 2 hypersensitivity reactions?

Answer 34

- activation of complement and formation of membrane attack complex (MAC) - antibody dependant cell mediated cytotoxicity (NK cell)

Question 35

what is type 3 hypersensitivity?

Answer 35

-antibody regulated reaction against soluble antigens circulating in serum

Question 36

type 3 hypersensitive reactions result in the for formation of what?

Answer 36

antibody-antigen immune complexes that are deposited in organs

Question 37

what effect do antibody-antigen immune complexes produced during type 3 hypersensitivity reactions have?

Answer 37

- activate complement - induce neutrophil recruitment - cause inflammatory damage

Question 38

give 3 examples of conditions associated with type 3 hypersensitivity reaction?

Answer 38

- arthus reaction - serum sickness - oral erythma multiforme (EM)

Question 39

is arthus reaction systemic or localised?

Answer 39

localised

Question 40

is serum sickness systemic or localised?

Answer 40

systemic

Question 41

what causes oral erythema multiform?

Answer 41

deposition of immune complexes (IgM) in microvasculature of oral mucosal membrane

Question 42

what are the symptoms of oral erythema multiform?

Answer 42

crusty blistering of oral mucosa

Question 43

hypersensitivity to injection causes which type of hypersensitivity response?

Answer 43

type 3

Question 44

which immune cell mediates type 4 hypersensitivity?

Answer 44

T cells (CD4 and CD8)

Question 45

delayed hypersensitivity refers to which type of hypersensitivity?

Answer 45

type 4

Question 46

why us type 4 hypersensitivity referred to as delayed hypersensitivity?

Answer 46

takes time to recruit T cells

Question 47

how is type 4 hypersensitivity tested?

Answer 47

patch test on back

Question 48

type 4 hypersensitivity has a role in which systemic diseases?

Answer 48

- crohns - TB - sarcoidosis