Part 13: Allergies

Question 1

type 1 hypersensitivity reactions are more commonly known as ___

Answer 1

allergic reaction

Question 2

type 1 hypersensitivity rxns involve ___ antibodies recognizing an antigen, causing the release of _____ from mast cells

Answer 2

igE; inflammatory mediators

Question 3

what are the 2 phases of igE mediated rxns?

Answer 3

1. sensitization phase and

2. the effector phase

Question 4

does the first exposure to an allergen typically generate an allergi response? why or why not

Answer 4

no, bc the immune system has never seen the antigen before, so it doesnt know what to do other tahn get rid of it

Question 5

if a new allergen arrives and there are other cytokines and activated helper T cells, ___ cells may be suspicious of the antigen and make igE antibodies against it. what is this process called?

Answer 5

B ; sensitization

Question 6

IgE antibodies are found at the surface of ___ cell

Answer 6

mast

Question 7

resting mast cells are typically found around the membrane barriers of the body such as the ___, ___, ____ and ___

Answer 7

skin, mucous membranes, respiratory tract and GI tract

Question 8

mast cells participate in ___ immune response, where they recruit other immune cells to the site of injury or infection

Answer 8

early

Question 9

what happens during a second exposure to an allergen that the body has already been sensitized to ?

Answer 9

IgE antibodies in the mast cells bind to the antigen and cause amst cell degranulation, releasing tons of histamines and other infalmmatory mediators and chemotactic cytokines

Question 10

the proinflammatory and cytokines produce immediate localized effects such as increased ____ and ___

Answer 10

vasodilation and vascular permeability

Question 11

what is the purpose of increasing vascular permeability and vasodilation in an allergic rxn?

Answer 11

recruit immune cells

Question 12

during an allergic rxn , there are increased secretions from the ___ and ___

Answer 12

GI tract, eyes etc

Question 13

during an allergic rxn, smooth muscle contraction can also occur in response to ___

Answer 13

mast cell degranulation

Question 14

contraction of smooth muscle in response to allergens results in allergic ____

Answer 14

asthma

Question 15

when mast cells release ___, ___, and ___ these mediators cause smooth muscle contraction and promote blood vessel permeability allowing immune cells in and the inflammation of the airwyas

Answer 15

histamine, prostaglandins, leukotrienes

Question 16

t/f immune responses are predictable and repeatable in a patient once the first reaction to allergen occurs

Answer 16

t

Question 17

allergic rhinitis

Answer 17

upper airways respond to exposure of an inhaled allergen

Question 18

when an allergic reaction is systemic it can be life-threatening and this is called ___

Answer 18

anaphylaxis

Question 19

in anaphylactic reaction, exposure to an allergen causes systemic ____, airway ____ and peripheral ___ which can result in respiratory arrest

Answer 19

inflammation; obstruction; edema

Question 20

what is desensitization therapy?

Answer 20

repeated microdosing of allergen to deplete IgE antibodies and decrease mast cell response over time

Question 21

what can an allergic rxn look like in the skin?

Answer 21

itchy rash, urticaria

Question 22

how can an allergic reaction present in the eyes?

Answer 22

redness, watering, itching

Question 23

how can an allergic reaction present in the lungs?

Answer 23

increased mucous secretions, bronchoconstriction

Question 24

how can an allergic reaction present in the GI tract?

Answer 24

cramping, bloating, diarrhea, nausea

Question 25

what happens to BP during anaphylaxis?

Answer 25

hypotensive

Question 26

how is an allergy test performed?

Answer 26

skin pricks to break skin barrier, then add a drop of a specific antigen as well as a positive control (histamine) and a negative control, then wait for mast cells to act (10-15min)

Question 27

why can antigens cause a greater allergic reaction than histamine alone?

Answer 27

amplification process of IgE on mast cells and recruiting more immune cells

Question 28

t/f a limitation of allergy testing is that there is not always every possible allergen available for testing

Answer 28

t

Question 29

what are the 2 pharm approaches to managing allergies

Answer 29

1. target the immune response to the allergen | 2. target the physiologic symptoms associated with that response

Question 30

what 3 classes of drugs are most often used in the setting of mild to moderate seasonal or environmental allergies

Answer 30

antileukotrienes, antihistamines, mast cell stabilizers

Question 31

drugs like antileukotrienes, antihistamines, and mast cell stabilizers reduce the ____ response to allergen but are insufficient in managing severe events like ____

Answer 31

inflammatory; anaphylaxis

Question 32

what are some of the physiologic symptoms of allergic rhinitis? what drugs can be used to manage them?

Answer 32

nasal congestion, runny nose; decongestants

Question 33

what drug is needed for anaphylaxis

Answer 33

epinephrine

Question 34

how does epinephrine help with anaphylaxis?

Answer 34

restores airway and increases cardiac output

Question 35

stimulation of alpha 1 adrenergic receptors causes

Answer 35

smooth muscle and blood vessel constriction

Question 36

stimulation of a1a receptors activates a ____ coupled signalling pathway

Answer 36

Gq

Question 37

what happens in cells when a1a receptor actiavtion in smooth muscle signals Gq activation?

Answer 37

DAG and IP3 increases, causing increase in intracellualr Ca 2, causing contraction

Question 38

what is the benefit of targeting A1A receptors in the sinuses?

Answer 38

constriction of the blood vessels, reducing leakiness and infiltration of immune cells, helping resolve congestion and runny nose

Question 39

phenylephrine is a ____ A1A receptor agonist

Answer 39

selective

Question 40

pseudophedrine is a ____receptor agonist

Answer 40

mixed alpha and beta adrenergic

Question 41

should phenylephrine and pseudophedrine be used long term?

Answer 41

no

Question 42

is there an issue with patients with hypertension taking phenylephrine or pseudophedrine?

Answer 42

not really recommended becease they are adrenergic agonists and may cause an increase in BP

Question 43

is the increase in BP caused by phenylephrine and pseudophedrine as noticeable in normotensive patients?

Answer 43

no, but some patients may experience palpations or tachycardia with pseudophedrine

Question 44

___ is the 1st key step in the initiation of allergic responses

Answer 44

mast cell degranulation

Question 45

if we can reduce the release of ___, we can dampen the allergic response

Answer 45

inflammatory mediators

Question 46

what is cromolyn?

Answer 46

mast cell stabilizer commonly available as an eye drop

Question 47

how do mast cell stabilizers like cromolyn work?

Answer 47

preventative by decreasing degranulation, thus reducing the initiation of the allergic response

Question 48

t/f mast cell stabilizers like cromolyn are not effective once the allergic response has started

Answer 48

t

Question 49

what is histamine?

Answer 49

one of many mediators released from mast cells upon IgE binding; it is an important allergic mediator

Question 50

t/f histamine on its own can elicit cellular responses

Answer 50

t

Question 51

blocking the cellular effects of histamine can significantly reduce the strength of many allergic responses, especially in the ___

Answer 51

respiratory tract

Question 52

antihistamines are ___ agonists of H1 receptors

Answer 52

inverse

Question 53

what does it mean that antihistamines are inverse agonists?

Answer 53

reduce the response below th enormal baseline

Question 54

why are antihistamines (inverse agonists) able to reduce response below the baseline?

Answer 54

preferentially bind to the inactive confirmation of the receptor, shifting the equilibrium towards the inactive form

Question 55

what are the effects of histamine?

Answer 55

vascular permeability, redness, itching and other pro-inflammatory effecst

Question 56

what is the most common first generation antihistamine?

Answer 56

diphenhydramine (Benadryl)

Question 57

what is a popular 2nd generation antihistamine?

Answer 57

loratadine (Claritin)

Question 58

Loratadine is a prodrug that transforms into ____ , which is also available as an antihistamine

Answer 58

desloratadine

Question 59

which genration antihistamines have a longer duration of action? what is the benefit?

Answer 59

second ; only need to be dosed Q 24 h

Question 60

what is the duration of action of 1st gen antihistamines?

Answer 60

6-8 hours

Question 61

which generation of antihistamine is able to cross the BBB?

Answer 61

first

Question 62

what is a CNS effect of 1st gen antihistamines?

Answer 62

bind to H1 in the CNS, causing drowsiness

Question 63

an off target of 1st gen antihistamines are ___ receptors

Answer 63

muscarinic

Question 64

why does diphenhydramine interact with muscarinic receptors?

Answer 64

shape resemble Ach

Question 65

what are the effects of 1st gen antihistamines when it blocks muscarinic receptors?

Answer 65

anticholinergic effects (antiemetic, motion sickness, vertigo)

Question 66

give an example of an LTRA

Answer 66

montelukast