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1

What is hypersensitivity?

Exaggerated or aberrant immune response to antigen resulting in inflammation and tissue damage.

2

What is Type I hypersensitivity?

Referred to as Allergy, atopy or immediate hypersensitivity.
- occurs mixtures after reexposure to antigen/allergen.
- Rapid IgE and mast cell mediated vascular and smooth muscle reaction that is often followed by inflammation.
*Affects 20% of population.

3

What is the basic sequence of events with Type I hypersensitivity?

1. Initial exposure to antigen and production of IgE = Sensitization.
- Th2 cells secrete IL's
- Th2 cell Cd40L binds to B cell Cd40
2. Binding of IgE Ab to Fc receptor on mast cells
3. Cross-linking of bound IgE upon reexposure to allergen.
4. Release of mast cell mediators

4

What are the immediate effects of Type I Hypersensitivity?

Dilation of blood vessels, increased vascular permeability, smooth muscle contraction.

5

What is the late response of Type I hypersensitivity?

Inflammation

6

What are the common allergens, Route of entry and response of Systemic anaphylaxis?

Common allergens: Drugs, venoms, peanuts & serum.

Route of entry: Intravenously or oral absorption

Response: Edema, increased vascular permeability, Tracheal occlusion, circulatory collapse, death.

7

What are the common allergens, Route of entry and response of Acute urticaria?

Common allergens: Animal hair, insect bites, allergy testing

Route of entry: Through skin

Response: Local increase in blood flow and vascular permeability.

8

What are the common allergens, Route of entry and response of Allergic Rhinitis?

Common allergens: Pollens & dust mite feces

Route of entry: inhalation

Response: Edema & irration of nasal mucosa

9

What are the common allergens, Route of entry and response of Asthma?

Common allergens: Danders, pollens, dust mite feces

Route of entry: inhalation

Response: Bronchial constriction, increased mucous production and airway inflammation

10

What are the common allergens, Route of entry and response of Food allergy?

Common allergens: Tree nuts, peanuts, shellfish, milk, eggs, fish.

Route of entry: oral

Response: vomiting, diarrhea, purtisis, urticaria (hives), anaphylaxis.

11

What are the 2 lipid mediators?

Prostanglandins & Leukotrienes

12

What are the 2 lipid mediators?

Prostaglandins & Leukotrienes

13

What do Prostaglandins do?

*Made via cyclooxygenase pathway
VASOCONSTRICTION in the LUNGS or dilation in vascular smooth muscle.
- Cause aggregation or disaggregation of platelets.

14

What do Leukotrienes do?

* Made in Lipoxygenase pathway
- Powerful inducer of BRONCHOCONSTRICTION, INCREASED VASCULAR PERMEABILITY.
*Refered to as slow reacting substance of anaphylaxis (SRS-A)

15

What are the 2 lipid mediators of mast cell Degranulation?

Prostaglandins & Leukotrienes

16

What is the immediate response of Mast Cell Degranulation?

Vasoactive amines (Histamine and serotonin) and proteases.
- synthesis and secretions of lipid mediators (prostaglandins and Leukotrienes made from arachidonic acid)

17

What is the late--phase rxn of Mast cell Degranulation?

- Synthesis and secretion of cytokines and chemokine.
- Infiltration of Eosinophils, monocytes and neutrophils.

18

What do ITAM's do?

Activate map kinase

19

Map kinases are important in the formation of what?

Cytokines

20

What are the most common signs of asthma?

coughing, wheezing, shortness of breath

21

What causes the narrowing of airways with asthma?

Inflamed muscle wall.

22

Treatment strategies for asthma?

- inhaled Corticosteroids (dampen inflammatory response)
- Leukotriene modifiers (block chain of reaction)
- Chromolyn =inhaled; prevents mast cell degranulation
- Theophylline = opens airways.

23

Treatment strategies for asthma?

- inhaled Corticosteroids (dampen inflammatory response)
- inhaled long acting beta2 agonists = receive inflammation.
- Leukotriene modifiers (block chain of reaction)
- Chromolyn =inhaled; prevents mast cell degranulation
- Theophylline = opens airways.

24

Intravenous antigen (gets into blood) causes what?

mast cell degranulation = systemic response = systemic anaphylaxis

25

Low does inhalation of antigen leads to what?

Hay fever symptoms

26

Low dose inhalation of antigen leads to what?

Hay fever symptoms

27

Enzymes released from mast cells cause what?

Tissue damgage

28

Cytokine & Lipid mediators released from mast cells cause what?

inflamation

29

Cytokine & Lipid mediators released from mast cells cause what?

inflammation

30

All clinical and pathological features of immediate hypersensitivity reactions are driven by ________.

Mediators produced by mast cells.