Week 2 Flashcards
Atopy is currently defined as?
Predisposition to produce IgE antibodies in response to the ordinary exposure to allergens in the environment
Who coined the term “allergy” to describe the phenomenon he had observed in which some patients, under certain conditions, developed an increased reactivity instead of immunity?
Austrian paediatrician, Clemens von Pirquet
Who proposed the term ‘atopy’ for the clinical manifestations of allergy such as hayfever and asthma in which ‘the individuals possess a peculiar capacity to become sensitive to certain proteins to which their environment and habits of life frequently expose them”.
In 1923, Coca and Cooke
Explain what is “reagin” when Prausnitz showed this in 1921
Prausnitz showed that atopic allergic sensitivity can be passively transferred from one individual to another by a serum factor
In 1967, what was the reagin known/named as?
Immunoglobulin E
Classically, allergic reactions are divided into four main types:
Gell and Coombs Types 1-4
Immediate or early reaction is defined when symptoms occur?
Occur within minutes of an immune reaction
Late reaction is when symptoms?
Start after hours
Delayed reaction is when symptoms are?
After days
Type 1 immediate reaction is caused by?
IgE and possibly IgG
Antigens which cause Type 1 reactions are called?
allergens
When the allergen reacts with IgE attached to the surface of the mast cell, what happens?
Mast cell degranulates and releases chemical mediators (histamine, SRS-A, ECF, PAF) responsible for the symptoms
Type 1 reactions depend on the presence of?
Specific IgE on high affinity receptors on mast cells.
There are also IgE receptors of both low and high affinity on other cell types, including?
Eosinophils and macrophages
Activated B cells (plasma cells) produce?
IgE
Activated B cells producing IgE which depends on exposure to the allergen and costimulation signalling via?
Activated T cells, which direct the B cell to the production of IgE
IgE synthesis results from?
Collaboration between a subset of T helper (Th) cells which produce IL-4, but not IFN-gamma (Th2 cells).
Th2 cells because of their ability to produce?
IL-5 and IL-4
IL-5 and IL-4 are responsible for the _____ which are often associated with?
Eosinophils; hyperproduction of IgE in allergic subjects
T-helper cells which do not produce IL-4 or which produce high concentrations of IFN-gamma do not support?
Do not support IgE synthesis
IFN-gamma can suppress?
Can suppress IL-4 dependent IgE synthesis
Regulatory T cells such as ___, ___ and ____ may also play a role in determining whether the response to ubiquitous environmental allergens is that of tolerance or of sensitisation and clinical allergy.
nTreg, Th3, and Tr1
Dysregulation of regulatory T cells (nTreg, Th3 and Tr1) is now thought to play a significant role in?
Development of the atopy
Promotion of a prevalent Th2 type response to environmental allergens (such as __, ____, ____, ____ etc) in atopic subjects almost certainly involves a genetic predisposition as well as environmental influences.
Foods, HDM, animal dander, pollen