Hypersensitivity I

Front 1

What mediates a type I hypersensitivity reaction?

Back 1

1. IgE---- mast cell activation and degranulation

Front 2

What are some examples of a type I hypersensitivity reaction?

Back 2

1. Hay fever

2. Asthma

3. Anaphylaxis

4. Atopic dermatitis

5. IgE-mediated eczema

Front 3

What mediates type II hypersensitivity reactions?

Back 3

1. IgM, IgG--- cytotoxic

2. Antibodies involved that are specific for that tissue

Front 4

What are some examples of type II hypersensitivity reactions?

Back 4

1. Autoimmune hemolytic anemias
2. ADCC
3. Goodpasture

Front 5

What mediates type III hypersensitivity reactions?

Back 5

1. Antibodies formed against exogenous or endogenous antigens

2. Complement often involved--- formed in serum or EC spaces

Front 6

What are some reactions are type III hypersensitivity?

Back 6

1. SLE

2. Glomerulonephritis

3. Serum sickness

Front 7

What mediates type IV hypersensitivity?

Back 7

1. Sensitized T cells stimulate cell-mediated reactions by macrophages----

2. Tc cells, NK cells, eosinophils, neutrophils

Front 8

What are some examples of type IV hypersensitivity?

Back 8

1. Granulomatous disease

2. Contact dermatitis

3. Graft rejection

Front 9

What is the mnemonic to help you remember the class of hypersensitivity reactions?

Back 9

1. ACID

2. Allery, Cytotoxic, Immune complex, Delayed

Front 10

How long does it take for ssx of type I hypersensitivity reactions take to present?

Back 10

1. Seconds to minutes

Front 11

What is released in type I hypersensitivity reactions?

Back 11

1. IgE--- basophils---- degranulation--- histamine

Front 12

What is atopy?

Back 12

1. Genetic predisposition to make IgE

Front 13

What does histamine do?

Back 13

1. Smooth muscle contraction

2. Mucus secretion

3. Increased GI fluid secretion

4. Vasodilation

5. Increased vascular permeability

Front 14

What local reactions occur in type I hypersensitivity reactions?

Back 14

1. Skin--- urticaria, pruritis, wheal and flare, eczema

2. Nasal mucosa--- allergic rhinitis

3. Lungs-- bronchial asthma

Front 15

How do you tx full-blown type I hypersensitivity reactions?

Back 15

1. Epinephrine

Front 16

What is the difference between anaphylactoid reactions and type I hypersensitivity reactions?

Back 16

1. No IgE in anaphylactoid reactions

Front 17

What are the anaphylatoxins?

Back 17

1. C5a

2. C3a

3. C4a

Front 18

What mediates anaphylactoid reactions?

Back 18

1. Anaphylatoxins

2. Calcium ionophores

3. Radiocontrast dyes

4. Opiates

5. Vancomycin

Front 19

What occurs in anaphylactoid reactions? (figure)

Back 19

Front 20

70% of all bronchial asthma is due to....

Back 20

1. Type I hypersensitivity reactions

Front 21

What are the medical syndromes associated with atopy?

Back 21

1. Inhalant allergies

2. Dermatitis

3. Allergic asthma

Front 22

What is the MC atopic disease?

Back 22

1. Allergic rhinitis

Front 23

What is the presentation of type I hypersensitivity reaction eczema?

Back 23

1. Pus-filled papillose with eosinophils OR

2. Dry, crusted lesions

Front 24

How do you tx eczema induced by I hypersensitivity reactions?

Back 24

1. Anti-histamines

2. Topical corticosteroids

Front 25

What ar the three pathological events that lead to allergic asthma?

Back 25

1. Reversible obstruction

2. Airway hyperreactivity to physical and chemical stimuli

3. Inflammation

Front 26

What is produced in inflammation in allergic asthma?

Back 26

1. ROS

2. NOS

3. Cytokines--- IL-4, IL-5 (eosinophil maturation)

Front 27

What is the key cell involved in cytokine secretion in allergic asthma?

Back 27

1. Helper T-cell

Front 28

What causes food allergies?

Back 28

1. Mast cell degranulation in GI tract

2. Ssx--- severe stomach pain, diarrhea, emesis, dyspnea, skin hives/urticaria

Front 29

When does the recurrent anaphylaxis occur in I hypersensitivity reactions? What causes it?

Back 29

1. Hours later

2. Leukotriene and prostaglandin production

Front 30

What are the MCC of anaphylaxis?

Back 30

1. Penicillin

2. Bee stings

3. Peanuts

Front 31

What are the stages of type I hypersensitivity reactions?

Back 31

1. Sensitization

2. Early phase

3. Late phase

Front 32

What occurs in the sensitivity stage of type I hypersensitivity reactions?

Back 32

1. Takes weeks

2. Initial contact with allergen

3. Th2 secretes IL-4 and ILI-13

4. B cell makes IgE

5. IgE binds FCER on mast cell

Front 33

What occurs in the early phase of type I hypersensitivity reactions?

Back 33

1. Occurs within 20 minutes of contact

2. Allergen cross-linkes IgE

3. Mast cell degranulates

4. Histamine is released

Front 34

What occurs in the late phase of type I hypersensitivity reactions?

Back 34

1. 6 hours later----

2. Newly formed mediators from arachadonic acid

Front 35

What histamine receptors are most involved in type I hypersensitivity reactions?

Back 35

1. H1

2. H2

Front 36

What does the lipoxygenase give rise to?

Back 36

1. Leukotrienes

Front 37

What is the effect of LTB4?

Back 37

1. Chemotaxis

2. Hyperalgesia

Front 38

What leukotrienes are in charge of bronchoconstriction and edema in type I hypersensitivity reactions?

Back 38

1. C4, D4, E4

Front 39

What is the function of PGE2?

Back 39

1. Vasodilation

Front 40

What is the function of TXA2?

Back 40

1. Platelet aggregation

Front 41

What is the function of PGI2?

Back 41

1. Inhibits platelet aggregation

2. Causes vasodilation

Front 42

What occurs in the formation of inflammatory cell infiltrate in type I hypersensitivity reactions?

Back 42

1. ECF, IL-8, LTB4--- recruitment of eosinophils and PMNs

2. Eosinophils degranulate when FCER is cross-linked by allergen and IgE

3. Destructive substances produced, injure epithelium

Front 43

What destructive substances are produced in the inflammatory cell infiltrate step?

Back 43

1. Major basic protein

2. Eosinophil cationic protein

3. ROS

Front 44

What makes up SRS-A?

Back 44

1. C4, D4, E4

Front 45

What inactivates SRS-A? When?

Back 45

1. Arylsulfatase

2. In last step of type I hypersensitivity reactions

Front 46

What deactivates histamine in the last step of type I hypersensitivity reactions?

Back 46

1. Histaminase

Front 47

What are the outcomes of the skin prick test?

Back 47

1. Wheal and flare 5-7 mm within 15 minutes is positive

2 Late response--- 5-6 h later

Front 48

What does the RAST test measure?

Back 48

1. Allergen-specific IgE

Front 49

What does the RIST measure?

Back 49

1. Total serum IgE

Front 50

What do you look for in a nasal smear?

Back 50

1. >10% eosinophils

Front 51

How can you prevent type I hypersensitivity reactions?

Back 51

1. Prevent exposure

2. Hyposensitizaiton tx

Front 52

What occurs in hyposensitization tx?

Back 52

1. Introduce allergen

2. Isotope switch from IgE to IgG4/IgA--- mast cells don't degranulate

3. Cause shift from TH2 to TH1

Front 53

What type of switch does sublingual administration of allergy meds cause?

Back 53

1. TH2 to T reg

Front 54

What is the function of tryptase in the early phase?

Back 54

1. Generate C3a and C5a