Mechanisms Of Hypersensitivity Type I - Bowden (completed)

Question 1

Which hypersensitivity is mediated by T cells? 4

Answer 1

Type IV hypersensitivity

Question 2

What are the preformed granules contained within Mast Cells? 7

Answer 2

Histamine (2-5 pg/cell)

Serotonin

Heparin

Serine Proteases

Question 3

Once activated, what are the newly formed lipid mediators? 7

Answer 3

Prostaglandin D2

Leukotrienes

Question 4

What’s another word for lipid mediators produced from Mast Cell? 7

Answer 4

Eicosanoids

Question 5

What Fc receptor does Mast Cells utilize? 7

Answer 5

FcεRI (CD 23a)

Question 6

What cytokines and chemokines do Mast Cells secrete? What do these cytokines do? 7

Answer 6

IL-4 & IL-13 –> stimulates and amplifies Th2 cell response

IL-3, IL-5, GM-CSF –> eosinophil production and activation

CCL3 (chemokine) –> attracts monocytes, macrophages,, and neutrophils

Question 7

What are some of the main actions of Mast Cells? 7

Answer 7

Increase vascular permeability

Smooth muscle contraction

Eosinophil production and activation

Activates platelets

Question 8

What is the major contributor to tissue damage during allergic inflammation? 8

Answer 8

Eosinophils

Question 9

What chemokines & cytokines do Eosinophils secrete? What do they do? 8

Answer 9

IL-3, IL-5, GM-CSF –> eosinophil activation and production

TGF-α, TGF-β –> epithelial proliferation

CXCL8 (IL-8) –> leukocyte chemotaxis

Question 10

What is the role of Eosinophil peroxidase and collagenase? 8

Answer 10

Eosinophil Peroxidase:
triggers histamine release from mast cells
halogenates and kills targets

Eosinophil Collagenase:
remodels connective tissue matrix

Question 11

What is the most pro-inflammatory leukotriene (SRS-A)? 9

Answer 11

LTB4

Question 12

Do leukotrienes come before or after histamine into the allergic reaction?

Answer 12

Slower onset, after

Question 13

What are the roles of Leukotrienes (SRS-A)? 9

Answer 13

increase capillary permeability

increase mucus production

bronchoconstriction (more powerful than histamine)

Lady Come Make Babies

Question 14

What are the roles of IL-4? 10

Answer 14

Th2 cell growth factor

Isotype switching to IgE

Increase of VCAM-1 expression

Question 15

What are the roles of IL-13? 10

Answer 15

airway eosinophilia (COPD, Asthma)

Mucous gland hyperplasia

airway fibrosis and remodeling

Question 16

What are the roles of IL-5? 10

Answer 16

regulates Eosinophil production and survival

Question 17

What are the roles of TNF? 10

Answer 17

recruits and activates inflammatory cells

alters function/growth of airway SM

Question 18

What are only cells in humans that contain histamine? 11

Answer 18

Mast cells and basophils

Question 19

What are the characteristics of Allergens? 12

Answer 19

Small and highly soluble

Carried via dry particles

No inflammation

Triggers Th2 response

Question 20

Describe sensitization to allergen? What is another word that describes this phase? 13

Answer 20

Also called priming

IgE specific to the allergen is mounted on a Mast Cell

(With next exposure the mast cells are able to immediately degranulate)

Question 21

What hypersensitivity is immediate?

Answer 21

Type I Hypersensitivity

Question 22

Within the first 5 minutes what happens within a primed individual exposed to the allergen?

Answer 22

Preformed mediator release:

Histamine
Heparin
Tryptase

Question 23

Within 5-30 minutes what happens within a primed individual exposed to the allergen? 14

Answer 23

Newly generated mediators:

Arachidonic Acid

Leukotriene D4

Prostaglandin D2

Question 24

Within hours what happens within a primed individual exposed to the allergen? 14

Answer 24

Cytokines release:

IL-4

TNFα

Question 25

What are the actions of histamine (biogenic amines)? 15

Answer 25

Vascular leak Bronchoconstriction Intestinal hypermotility

Question 26

What is the action of Tryptase within a type I hyper sensitivity? 15

Answer 26

Tissue damage

Question 27

What are the products excreted from eosinophils? 15

Answer 27

Eosinophil Collagenase Eosinophil peroxidase Major Basic Protein (MBP, cationic granule) Eosinophil cationic protein (cationnic granule)

Question 28

What are the common examples of type I hypersensitivity? 16

Answer 28

Anaphylaxis Acute Urticaria (animal hair, insect bites, allergen testing) Seasonal Rhinoconjunctivitis (hay fever) Food Allergy

Question 29

What happens during the Early phase of an Immediate Acute Atopic Response? 17

Answer 29

Allergen introduced Cross-linking between two mIgE Symptoms show Inflammatory cells recruited by Mast cell cytokines

Question 30

What are the early phase (immediate) symptoms of an acute atopic response? 17

Answer 30

Sneezing Pruiritis Rhinorrhea Congestion

Question 31

What happens during the Late phase of an Immediate Acute Atopic Response? 17

Answer 31

Influx and activation of: eosinophils, neutrophils, basophils, and Th2 10x increase in [Mast Cell] w/ increased Fcε expression Systemic symptoms

Question 32

What are unwanted consequences of Eosinophils? 18

Answer 32

local tissue damage CHES - chronic hyperplastic eosinophilic sinusitis

Question 33

What are the systemic symptoms that present during the last phase of a chronic atopic response? 18

Answer 33

fatigue myalgia asthma

Question 34

Define Atopic Asthma? 19

Answer 34

airway hyper-responsiveness characterized by BHR (Bronco-hyper reactivity)

Question 35

What happens in systemic anaphylaxis? 20

Answer 35

dramatic increase in vascular permeability and constriction of smooth muscle Pt can't breath, vomitting, diarrhea, low BP

Question 36

What are the five leukotrienes?

Answer 36

LTC4 LTD4 LTE4 LTB4 (pro-inflammatory)