Lecture 23: Allergy Flashcards
Which lymphocytes and cytokines are very important in allergy responses
Th2 cells, IL-4, 5, 13
NB! Allergens are a diverse group of ___ and _______
Proteins and glycoproteins
Which receptors are commonly activated in allergic responses
PRRs
What plays an important role in allergens being able to cross the skin/mucosa
Protease activity of the allergen
Atopy is most easily defined as
The presence of a type I hypersensitivity reaction to an allergen
-Or the propensity for developing immediate hypersensitivity reactions to common environmental allergens
Which genes are known to be involved in predisposition to allergy
B chain of high affinity receptor for IgE (FceRIB)
IL-4 gene
HLA-DR genes
CD14 gene
What is CD14
It constitutes part of the receptor for bacterial LPS
What plays larger role in allergies- environment or genes
Environment
Hygiene hypothesis suggests what as the cause of increasing prevalence of allergy
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
Neonatal immune system shows bias towards Th1 or Th2- how do infections early in life affect this
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
Mast cells, basophils, eosinophils- Where do each of them mature and can they be found in circulation?
Which has longest life span
Basophil, Eosinophil- Mature in bone marrow, Yes
Mast cell- Mature in CT, not found it circulation
Mast cells live weeks to months
Major development factor for mast cells, eosinophils and basophils
Mast cells- Stem cell factor, IL-3
Basophils- IL-3
Eosinophils- IL-5
Mast cell granule contents
Histamine, heparin sulfate and or chondroitin sulfate, proteases
Basophil granule contents
Histamine, chondroitin sulfate, proteases
Eosinophil granule contents
Major basic protein, peroxidases, hydrolases, lysophospholipase
Expression of FceRI on mast cell, basophils, eosinophils
Mast cell- High
Basophil- High
Eosinophil- Low
Amine and lipid mediators released by mast cells and basophils cause an immediate response including
Vascular leakage, bronchoconstriction and intestinal hypermotility
Allergens stimulate DCs to produce
IL-4
Allergens are typically presented on Class __ MHC
Class II
Th2 cells produce what cytokines after clonal expansion/activation- and they do what
IL-4 and IL-13
Activate B cells to become plasma cell secreting IgE
FceRI has high affinity for
Fc of IgE
What happens to IgE and FceRI structurally that ultimately leads to activation of the cell
Cross linking of the receptors
Effects of histamine
Smooth muscle contraction, vascular permeability
Effects of tryptase
Anaphylaxis, urticaria
Effects of bradykinin
Vasodilator, smooth muscle contraction
Inflammatory mediators can cause what chronic structural changes to the airway
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
What cytokine(s) is/are involved in airway hyperresponsiveness
IL-13
IgG blocking antibodies work how in desensitization
Repeat exposure to desensitizing allergen causes increased IgG Ab development, which compete with pathogenic IgE for allergen binding
Desensitization provokes immunoregulation how
Exposure to repeated desensitizing allergen induces Treg cells, which recognize allergen but invoke regulatory immune responses, dampening migration, infiltration and inflammation
Desensitization causes immune deviation- shifting from ___ to ____
Shifts away from Th2 and towards Th1 producing CD4 cells, increases production of IFN-y which inhibits IgE production
