Lecture 23: Allergy

Question 1

Which lymphocytes and cytokines are very important in allergy responses

Answer 1

Th2 cells, IL-4, 5, 13

Question 2

NB! Allergens are a diverse group of ___ and _______

Answer 2

Proteins and glycoproteins

Question 3

Which receptors are commonly activated in allergic responses

Answer 3

PRRs

Question 4

What plays an important role in allergens being able to cross the skin/mucosa

Answer 4

Protease activity of the allergen

Question 5

Atopy is most easily defined as

Answer 5

The presence of a type I hypersensitivity reaction to an allergen
-Or the propensity for developing immediate hypersensitivity reactions to common environmental allergens

Question 6

Which genes are known to be involved in predisposition to allergy

Answer 6

B chain of high affinity receptor for IgE (FceRIB)
IL-4 gene
HLA-DR genes
CD14 gene

Question 7

What is CD14

Answer 7

It constitutes part of the receptor for bacterial LPS

Question 8

What plays larger role in allergies- environment or genes

Answer 8

Environment

Question 9

Hygiene hypothesis suggests what as the cause of increasing prevalence of allergy

Answer 9

Shift from Th1 to Th2 type of immunity
Decreased number/activity of Treg cells
Increased incidence of allergy is associated with decreased exposure to common infections in early life

Question 10

Neonatal immune system shows bias towards Th1 or Th2- how do infections early in life affect this

Answer 10

Th2 - infection early in life can cause Th1 response and restore the Th1/Th2 balance
Increase in Treg cells after infections can limit the development of unrelated allergies

Question 11

Mast cells, basophils, eosinophils- Where do each of them mature and can they be found in circulation?
Which has longest life span

Answer 11

Basophil, Eosinophil- Mature in bone marrow, Yes
Mast cell- Mature in CT, not found it circulation
Mast cells live weeks to months

Question 12

Major development factor for mast cells, eosinophils and basophils

Answer 12

Mast cells- Stem cell factor, IL-3
Basophils- IL-3
Eosinophils- IL-5

Question 13

Mast cell granule contents

Answer 13

Histamine, heparin sulfate and or chondroitin sulfate, proteases

Question 14

Basophil granule contents

Answer 14

Histamine, chondroitin sulfate, proteases

Question 15

Eosinophil granule contents

Answer 15

Major basic protein, peroxidases, hydrolases, lysophospholipase

Question 16

Expression of FceRI on mast cell, basophils, eosinophils

Answer 16

Mast cell- High
Basophil- High
Eosinophil- Low

Question 17

Amine and lipid mediators released by mast cells and basophils cause an immediate response including

Answer 17

Vascular leakage, bronchoconstriction and intestinal hypermotility

Question 18

Allergens stimulate DCs to produce

Answer 18

IL-4

Question 19

Allergens are typically presented on Class __ MHC

Answer 19

Class II

Question 20

Th2 cells produce what cytokines after clonal expansion/activation- and they do what

Answer 20

IL-4 and IL-13

Activate B cells to become plasma cell secreting IgE

Question 21

FceRI has high affinity for

Answer 21

Fc of IgE

Question 22

What happens to IgE and FceRI structurally that ultimately leads to activation of the cell

Answer 22

Cross linking of the receptors

Question 23

Effects of histamine

Answer 23

Smooth muscle contraction, vascular permeability

Question 24

Effects of tryptase

Answer 24

Anaphylaxis, urticaria

Question 25

Effects of bradykinin

Answer 25

Vasodilator, smooth muscle contraction

Question 26

Inflammatory mediators can cause what chronic structural changes to the airway

Answer 26

Activation of tissue fibroblasts, increased collagen Increased mucus production by goblet cells Smooth muscle hyperplasia and hypertrophy Increased risk of acute obstruction of airflow in lungs in response to allergens/irritants

Question 27

What cytokine(s) is/are involved in airway hyperresponsiveness

Answer 27

IL-13

Question 28

IgG blocking antibodies work how in desensitization

Answer 28

Repeat exposure to desensitizing allergen causes increased IgG Ab development, which compete with pathogenic IgE for allergen binding

Question 29

Desensitization provokes immunoregulation how

Answer 29

Exposure to repeated desensitizing allergen induces Treg cells, which recognize allergen but invoke regulatory immune responses, dampening migration, infiltration and inflammation

Question 30

Desensitization causes immune deviation- shifting from ___ to ____

Answer 30

Shifts away from Th2 and towards Th1 producing CD4 cells, increases production of IFN-y which inhibits IgE production