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Allergic Asthma Information
IgE and Its Role in Allergy and
Allergic Asthma
Allergic asthma is made worse by inhaling allergens (pollens, mold,
etc.) to which the asthma suffer is allergic. This causes the nasal
passages and/or the airways of the lungs to become swollen. This
inflammation results in the release of chemicals, or mediators, into
the bloodstream. The key to this inflammatory process is an antibody
called IgE (Immunoglobulin E).
In 1921, two researchers named Carl Prausnitz and Otto Küstner
discovered that susceptibility to develop allergies could be
transferred from one individual to another by a blood transfusion.
When the allergen, or the substance that caused the allergy, was
applied to the person who previously did not suffer from allergies, he
developed signs of an allergic reaction. Fifty years later, it was
discovered that IgE in the blood was responsible for this transfer of
the allergic response from an allergic person to someone who did not
have allergies previously.
An allergy develops when a person becomes “sensitized” to an allergen,
such as pollen. In allergic asthma, the allergen is inhaled into the
respiratory tract (nose, throat and lungs) and attaches to the mucous
membrane. If a person is allergic to the allergen, T-cells
(T-lymphocytes) in the body prepare to fight it off. The T-cells then
send a signal to B-cells (B-lymphocytes), initiating the production of IgE antibodies, substances that defend the body against allergens.
For every allergen that enters the body of a person who is allergic to
that allergen, specific IgE antibodies are produced within a few weeks
of the first exposure and released into the bloodstream. Each IgE is
specific to an allergen; therefore, a person with multiple allergies
will have IgE’s for each of them. Some IgE antibodies attach to mast
cells, which line the skin, nose, intestines and bronchial tubes,
while others remain free floating in the bloodstream.
When an allergic individual is exposed to an allergen, IgE recognizes
the foreign substance and binds it to a mast cell. This binding of IgE
and allergen to the mast cell triggers the mast cell to release
inflammatory mediators, such as histamine, prostaglandins and
leukotrienes which, in turn, cause symptoms such as bronchial
constriction, coughing and wheezing. The release of these inflammatory
substances plays a major role in allergic diseases, such as allergic
asthma.
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