Asthma inflammation and allergy Flashcards
What are allergens?
Antigens that elicit an allergic response
What is anaphylaxis?
Acute severe allergic reaction resulting in respiratory collapse
What are the inflammatory extrinsic features of allergy and asthma?
Atopic
Young onset
Hyperresponsive
What are the inflammatory intrinsic features of allergy and asthma?
Non-atopic
Middle aged +
Hyperresponsive
More severe airflow limitation
What is the development of allergy driven by?
T helper lymphocyte subset (Th2 cells) and their products (Th2 cytokines)
What cytokines do Th1 produce?
Interferon-y
IL-12
What cytokines do Th2 produce?
IL-4 and IL-13
IL-5
IL-9
What factors favour the Th1 phenotype?
Presence of older siblings
Early exposure to day care
TB, measles or hep A infection
Rural environment
What factors favour Th2 phenotype?
Widespread use of antibiotics Western lifestyle Urban environment Diet Sensitisation to house dust mites and cockroaches
Th1 cytokines stimulate or express Th2 production?
suppress
Which cytokines switch B lymphocytes to make IgE antibody?
IL-4 and IL-13
IgE fixes onto what on the surface of tissue mast cells?
FceR
Which immunoglobulin is relatively rare in plasma?
IgE
What does E stand for in IgE?
Erythematous
What causes degranulation of mast cells?
Cross linking of FceR1-bound IgE on the mast cell surface
What are the mast cell products?
Histamine
TNF & other cytokines
Proteases
Heparins
Which mast cells have low histamine?
Lung
Which mast cells have high histamine?
Skin
Name 3 membrane derived lipid mediators of inflammation
Leukotrienes
Prostanoids
PAF
What role do LTC4 and LTD4 have in asthma?
Potent constriction of airway smooth muscle
Increase vascular permeability
What role do LTB4 have in asthma?
No direct bronchoconstriction
Chemotactic for leukocytes
What role does PGE2 have in asthma?
Relaxes airway smooth muscle
May decrease leukocyte activation
Sensitises irritant receptors
What role does PGD2 have in asthma?
Chemotactic
Bronchoconstrictor
What are the actions of IL-13 (and IL-4)?
Increase eosinophil adhesion and migration.
Increase mucus secretion.
Tissue remodelling.
Increase airway smooth muscle cotractility
