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HDM - Final > Mechanisms Of Hypersensitivity Type I - Bowden (completed) > Flashcards

Mechanisms Of Hypersensitivity Type I - Bowden (completed) Flashcards

1
Q

Which hypersensitivity is mediated by T cells? 4

A

Type IV hypersensitivity

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2
Q

What are the preformed granules contained within Mast Cells? 7

A

Histamine (2-5 pg/cell)

Serotonin

Heparin

Serine Proteases

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3
Q

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

A

Prostaglandin D2

Leukotrienes

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4
Q

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

A

Eicosanoids

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5
Q

What Fc receptor does Mast Cells utilize? 7

A

FcεRI (CD 23a)

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6
Q

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

A

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

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7
Q

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

A

Increase vascular permeability

Smooth muscle contraction

Eosinophil production and activation

Activates platelets

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8
Q

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

A

Eosinophils

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9
Q

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

A

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

TGF-α, TGF-β –> epithelial proliferation

CXCL8 (IL-8) –> leukocyte chemotaxis

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10
Q

What is the role of Eosinophil peroxidase and collagenase? 8

A

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

Eosinophil Collagenase:
remodels connective tissue matrix

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11
Q

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

A

LTB4

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12
Q

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

A

Slower onset, after

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13
Q

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

A

increase capillary permeability

increase mucus production

bronchoconstriction (more powerful than histamine)

Lady Come Make Babies

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14
Q

What are the roles of IL-4? 10

A

Th2 cell growth factor

Isotype switching to IgE

Increase of VCAM-1 expression

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15
Q

What are the roles of IL-13? 10

A

airway eosinophilia (COPD, Asthma)

Mucous gland hyperplasia

airway fibrosis and remodeling

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16
Q

What are the roles of IL-5? 10

A

regulates Eosinophil production and survival

17
Q

What are the roles of TNF? 10

A

recruits and activates inflammatory cells

alters function/growth of airway SM

18
Q

What are only cells in humans that contain histamine? 11

A

Mast cells and basophils

19
Q

What are the characteristics of Allergens? 12

A

Small and highly soluble

Carried via dry particles

No inflammation

Triggers Th2 response

20
Q

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

A

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)

21
Q

What hypersensitivity is immediate?

A

Type I Hypersensitivity

22
Q

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

A

Preformed mediator release:

Histamine
Heparin
Tryptase

23
Q

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

A

Newly generated mediators:

Arachidonic Acid

Leukotriene D4

Prostaglandin D2

24
Q

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

A

Cytokines release:

IL-4

TNFα

25
Q

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

A

Vascular leak

Bronchoconstriction

Intestinal hypermotility

26
Q

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

A

Tissue damage

27
Q

What are the products excreted from eosinophils? 15

A

Eosinophil Collagenase

Eosinophil peroxidase

Major Basic Protein (MBP, cationic granule)

Eosinophil cationic protein (cationnic granule)

28
Q

What are the common examples of type I hypersensitivity? 16

A

Anaphylaxis

Acute Urticaria (animal hair, insect bites, allergen testing)

Seasonal Rhinoconjunctivitis (hay fever)

Food Allergy

29
Q

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

A

Allergen introduced

Cross-linking between two mIgE

Symptoms show

Inflammatory cells recruited by Mast cell cytokines

30
Q

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

A

Sneezing

Pruiritis

Rhinorrhea

Congestion

31
Q

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

A

Influx and activation of: eosinophils, neutrophils, basophils, and Th2

10x increase in [Mast Cell] w/ increased Fcε expression

Systemic symptoms

32
Q

What are unwanted consequences of Eosinophils? 18

A

local tissue damage

CHES - chronic hyperplastic eosinophilic sinusitis

33
Q

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

A

fatigue

myalgia

asthma

34
Q

Define Atopic Asthma? 19

A

airway hyper-responsiveness

characterized by BHR (Bronco-hyper reactivity)

35
Q

What happens in systemic anaphylaxis? 20

A

dramatic increase in vascular permeability and constriction of smooth muscle

Pt can’t breath, vomitting, diarrhea, low BP

36
Q

What are the five leukotrienes?

A

LTC4

LTD4

LTE4

LTB4 (pro-inflammatory)

HDM - Final (15 decks)

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