Allergies & IgE Activation

[j_thomas]

Allergies are abnormal immune responses to allergens like pollen
grains, dust, moulds and foodstuffs. Allergens cause abnormal
production of immunoglobulin E (IgE). When the antigen makes contact
with some part of the body, it is taken up, processed by Antigen
Presenting Cell (APC) and presented on a Class II MHC to Helper cells.
In the early stages of allergy, a type I hypersensitivity reaction
against an allergen, encountered for the first time, causes a response
in the T helper cells. These T helper cells produce cytokines which
stimulate B-cells to produce large amount of IgE, which circulates in
the blood and binds to an IgE-specific receptor on the surface of mast
cells and basophils. During second exposure, antigen binds to the IgE
antibodies on the mast cells, which undergo degranulation to release
histamine and other inflammatory chemical mediators into the
surrounding tissue causing symptoms like Nasal Stuffyness, Sneezing,
Runny nose, Watery eyes and mucous discharge. This animation
delineates the process of immune response on encounter with an
allergen


http://www.biosolutions.info/2012/02/allergies-ige-activation.html