Hypersensitivity I

Question 1

When is hypersensitivity seen?

Answer 1

second exposure

Question 2

Type I

Answer 2

Ab mediated - IgE

Question 3

Type II

Answer 3

Ab mediated

Question 4

Type III

Answer 4

Immune complex mediated

Question 5

Type IV

Answer 5

T cells/Macs

Question 6

Components of Type I

Answer 6

IgE - allergen specific
Mast cells 
Allergen
Eosinophils
CD4+ Th2 cells

Question 7

another word for allergy

Answer 7

atopy

Question 8

how is allergen introduced into the body

Answer 8

inhaled
eaten
administered as drugs

Question 9

Sensitization

Answer 9

first expo to allergen

activate Th2 cells and stimulation of IgE class switching in B cells

– IgE produced by plasma cell –> binds to FceRI on mast cells

Question 10

which cytokine induces class switch to IgE

Answer 10

IL-4

Question 11

Activation of mast cells

Answer 11

repeat expo to allergen: Ag crosslinked with IgE/FceRI – activation – PREFORMED mediators released

Question 12

what is released to induce immediate hypersenstivity reaction in Type I

Answer 12

Vasoactive amines, synthesis of lipid mediators

acts on vascular smooth muscle

Question 13

what is released to induce late-phase hypersenstivity reaction in Type I

Answer 13

cytokines

inflammation

Question 14

what is also activated via cross linking in addition to mast cells?

Answer 14

basophils

Question 15

Biologic effects of mast cells mediators:

Biogenic amines: histamines

Answer 15

vasodilation

vascular leak

Question 16

Biologic effects of mast cells mediators:

lipid mediators

Answer 16

bronchoconstriction
intestinal hypermotility
inflammation

Question 17

Biologic effects of mast cells mediators:

IL-5

Answer 17

inflammation

Question 18

Biologic effects of mast cells mediators:

enzymes

Answer 18

tissue damage

Question 19

Late phase reaction

Answer 19

IL-5 (from mast cells and Th2 cells): recruit and activate eosinophils

4-8 hrs later, lasts 1-2 days

Question 20

What does eosinophil help with?

Answer 20

Killing of parasites/host cells

tissue modeling

Question 21

What characterizes immediate reaction? Late phase?

Answer 21

Mast cell degranulation – wheel and flare

Eosinophils

Question 22

Local reactions - Type I, immediate

Answer 22

allergic rhinitis/sinusitis (hay fever)
food allergies
bronchial asthma
anaphylaxis

Question 23

Systemic anaphylaxis

Answer 23

Ag in blood –> tissue and activates CT mast cells throughout the body–> degranulation and mediators released

• Heart and vascular sys: inc permeability/fluid entry, anaphylactic shock
• respiratory tract: SM contraction, constriction of airways
• GI tract: contraction of muscle/diarrhea

Question 24

Progression of allergic sx with age

Answer 24

atopic dermatitis (eczema) and GI disorders —> rhinitis –> asthma –> adult asthma

IgE!

Allergy March

Question 25

Skin test

Answer 25

intro of Ag into skin Wheal and Flare w/in 20 min

Question 26

what is occuring in wheal

Answer 26

bump vasodilation and congestion

Question 27

Allergen-specific IgE testing

Answer 27

- kids afraid of skin test - ptns with skin conditions - don't want to stop taking anti-histamines NOT a screening test

Question 28

How is Allergen-specific IgE test done?

Answer 28

Plate coated with allergen - allergen specific | then patients serum is added and labeled with anti-e

Question 29

How are the IgE levels with Allergen-specific IgE test?

Answer 29

wide variability inc in variety of disease states age-related standards need to be used

Question 30

Serum IgE levels

Answer 30

ELISA method TOTAL serum IgE

Question 31

Total serum IgE testing

Answer 31

solid surface with anti-IgE antibody | then patient's serum added and labeled with anti-e

Question 32

whats the problem with total serum IgE test?

Answer 32

not specific enough

Question 33

Therapy for Type I

Answer 33

avoid allergen, drugs Immunotherapy

Question 34

What is immunotherapy

Answer 34

increasing doses of allergens are injected subcutaneously rise in IgG -- blocking seasonal rise in IgE Abs and a slow decline in the level of specific IgE . IgG binds Ag instead!

Question 35

What is immunotherapy not very effective against?

Answer 35

asthma

Question 36

What is occuring during immunotherapy?

Answer 36

Desensitization Rise in IgG and IgG4, decline in IgE over the course of about 2 years