Lecture 27: Type I Hypersensitivities

Question 1

hypersensitivity

Answer 1

exaggerated, innapropraiate or prolonged immune response to an antigen (or allergen)

Question 2

2 phases of hypersensitivity

Answer 2

• sensitization
• effector

Question 3

clinical manifestations of hypersensitivities plus any tissue damage that may result are due to….

Answer 3

immune response to the allergen

Question 4

hypersensitivity reactions are recognized based on the _____ of immune response and the _____ of the target antigen

Answer 4

type, location

Question 5

Type I hypersensitivity is ________ and mediated by _______

Answer 5

immediate, IgE

Question 6

Type II hypersensitivity is _______ and mediated by_____or_____

Answer 6

cytotoxic, IgG or IgM

Question 7

What is Atopy

Answer 7

inappropriate hypersecretion of IgE in response to allergens

individuals w/ atopy are atopic

Question 8

what is the hygiene hypothesis of atopy

Answer 8

preveleance of atopic disorders increses as the environemnt becomes more hygienic (lack of microbial diversity)

Question 9

In Type I sensitization phase, the initial exposure to allergen elicits a _____response

Answer 9

TH2

Question 10

B-cell activation results in secretion of ______

Answer 10

IgE

Question 11

IL____&____, secreted from effector Th2 cells induce class-switching to ______

Answer 11

IL-4 & IL-13, IgE

Question 12

IgE binds into ______ on the surface of mast cells, causing mast cells to become sensitized

Answer 12

FcεRs

Question 13

mature mast cells reside in _____ throughout the body

Answer 13

Connective tissue

Question 14

are there any clinical manifestations during the sensitization phase

Answer 14

no

Question 15

During the Effector Phase, on ____exposure to the same allergen, the allergen ______ IgE bound FcεRs on mast cells

Answer 15

repeat, crosslinks

Question 16

Mast cell activation results in…

Answer 16

• Release of granular contents (histamine)
• Synthesis and release of other mediators (Lipid mediators, cytokines)

Question 17

Granules contain preformed ______ & ________

Answer 17

histamine & proteases

Question 18

what is the major mediator in granules

Answer 18

histamine

Question 19

biological effects of histamine occur within ________ and is part of the ______Phase reaction

Answer 19

seconds, early phase reaction

Question 20

biological effects of histamine include

Answer 20

• vasodilation
• increased vascular permeability
• non-vasculature sm contraction
• increased mucus secretion

Question 21

Histamine binds to _____receptors

Answer 21

H1

Question 22

_______block histamine binding to H1 receptors

Answer 22

Antihistamines

Question 23

Mast cells begin to synthesize _____ and _____ within minutes of stimulation

Answer 23

prostaglandins (PGs) and leukotrienes (LTs)
biological effects are similar to histamine, but much more potent and longer-lasting

Question 24

corticosteroids inhibit the synthesis of ______and ______

Answer 24

PGs and LTs

prednisone, prednisolone, dexamethasone

Question 25

NSAIDs block the synthesis of .....

Answer 25

PGs | carprofen, meloxicam, deracoxib

Question 26

main cytokines synthesized by mast cells

Answer 26

**INF and IL-6**: inflammation **IL-4 & IL-13:** Th2, IgE **IL-5:**Eosinophils | several hours after stimulation by allergen

Question 27

cytokines are responsible for the ____phase reaction

Answer 27

late

Question 28

cytokines cause inflammatory response by recruiting and activating _______and _______

Answer 28

neutrophils & eosinophils | can cause tissue damage

Question 29

what are corticosteroids used to prevent

Answer 29

damaging inflammation caused by inflammatory cytokines

Question 30

acute, hypersensitive allergic reaction to an antigen

Answer 30

Anaphylaxis reactions manifest differently based on **location** of the allergen

Question 31

localized anaphylaxis

Answer 31

**local release of mediators** - clinical manifestations depend on site of allergen exposure and location of mast cell activation

Question 32

Systemic anaphylaxis

Answer 32

**systemic release of mediators** - systemic clinical manifestations result from the allergen being in/spread throughout the **bloodstream **

Question 33

**allergic rhinitis and allergic conjunctivitis** are a result of activation of mast cells where

Answer 33

upper respiratory tract and eyes | itchy, watery eyes, sneezing, runny nose

Question 34

treatments for allergic rhinitis and allergic conjunctivitis include..

Answer 34

**antihistamines** and **corticosteroids** (also antimicrobials if infection inspected)

Question 35

allergic asthma is a result of mast cell activation where

Answer 35

**lower respiratory** tract causing bronchocontriction and increased mucous secretion | coughing, wheezing, open mouth breathing

Question 36

treatment for allergic asthma includes..

Answer 36

**bronchodilators**(fast acting) **corticosteroids** (prevent late stage response)

Question 37

Atopic dermatitis and urticaria (Hives) results from mast cell activation where

Answer 37

in the skin (complications often due to self trauma - hair loss, scaling, hyperpigmentation, secondary infections) | itchy, red, dry, inflammed skin lesions

Question 38

treatments for atopic dermatitis and urticaria include

Answer 38

* corticosteroids * antihistamines * cyclosporine A * oclacitini * lokivetmab

Question 39

Food allergies result from activation of mast cells where...

Answer 39

GI Tract

Question 40

treat systemic anaphylaxis with ______ first

Answer 40

epinephrine - vasoconstriction - relaxes bronchial sm - increases HR and BP - inhibits mast cell degranulation | adjunctive txt include: antihistamines, corticosteroids, bronchodilators

Question 41

Intradermal skin tests observes development of _____and _____

Answer 41

wheal and flare

Question 42

immunoassays can be performed to measure total_____ or allergen-specific____levels within the serum

Answer 42

IgE, IgE

Question 43

what is allergen immunotherapy (hyposensitization therapy) and what is the goal

Answer 43

administration of increases doses of allergen goal is to alter the immune response to the allergen

Question 44

allergen immunotherapy results in the induction of Treg cells that function to suppress what

Answer 44

* mast cells, basophils, eosinophils * effector helpter T cells (esp Th2) * tissue inflammation and mucous production * inflammatory DCs

Question 45

Suppressing Th2 cells decreases _____production by B-cells and promotes_______production

Answer 45

IgE, IgG

Question 46

Type III hypersensativities are ________mediated cytotoxicity

Answer 46

immune mediated (IgG or IgM)

Question 47

Type IV hypersensativity is _______type and ______Cell mediated

Answer 47

delayed T-cell mediated

Question 48

mast cell activation causes the release of lipid mediators which synthesize ________ & _________

Answer 48

prostaglandins and leukotrienes