Allergy
According
to EPA
"microorganisms, such
as viruses, bacteria, and mold ...can cause disease, trigger allergic
reactions, and continue to damage materials long after the flood."
epa.gov
Allergy,
hypersensitive reaction by the body to foreign substances (antigens)
that in similar amounts and circumstances are harmless within the bodies
of other people.
Antigens that provoke an allergic
reaction are called
allergens. Typical
allergens include pollens, drugs, lints, bacteria, foods, and dyes or
chemicals. The immune system contains several mechanisms that normally
protect the body against antigens. Prominent among these are the
lymphocytes, cells
that are specialized to react to specific antigens. There are two kinds of
lymphocytes--
B cells and T
cells. B cells produce antibodies, which are proteins that bind to and
destroy or neutralize antigens. T cells do not produce antibodies;
instead, they bind directly to an antigen and stimulate an attack on it.
Allergic reactions can have immediate or delayed effects, depending on
whether the antigen triggers a response by B cells or T cells.
Allergic reactions with immediate
effects are the result of
antibody-antigen
responses (i.e., they are the products of B-cell stimulation).
These can be divided into three basic types.
Type I reactions, which include
hay fever, insect venom allergy, and asthma, involve the class of
antibodies known as
immunoglobulin E (IgE).
IgE molecules are bound to
mast cells, which
are found in loose connective tissue. When enough antigen has bound with
the IgE antibodies, the mast cells release granules of histamine and
heparin and produce other agents such as the leukotrienes. These potent
chemicals dilate blood vessels and constrict bronchial air passages.
Histamine is
responsible for the visible symptoms of an allergic attack, such as
running nose, wheezing, and tissue swelling. A severe, often fatal, type I
allergic reaction is known as
anaphylactic shock.
The predisposition of a person to type I allergic reactions is genetically
determined. The best protection against such allergies is avoidance of the
offending substance. Antihistamine drugs are often used to give temporary
relief. Another helpful measure is
desensitization, in
which increasing amounts of the antigen are injected over a period of time
until the sufferer no longer experiences an allergic response.
Type II reactions result when
antibodies react with antigens that are found on certain "target" cells.
The antigens may be natural components of healthy cells, or they may be
extrinsic components induced by drugs or infectious microbes. The
resultant antigen-antibody complex activates the
complement system,
a series of potent enzymes that destroy the target cell.
Type III reactions result when a
person who has been strongly sensitized to a particular antigen is
subsequently exposed to that antigen. In a type III reaction, the
antigen-antibody complex becomes deposited on the walls of the small blood
vessels. The complex then triggers the complement system, which produces
inflammation and vascular damage. Unlike type I reactions, type II and
type III reactions are not dependent on a genetic predisposition.
Avoidance of known allergens is the best protection against such
reactions.
Delayed, or type IV, allergic
reactions are caused by the actions of T cells, which take longer to
accumulate at the site where the antigen is present than do B-cell
antibodies. The allergic responses appear 12 to 24 hours or more after
exposure to an appropriate antigen. A common
delayed allergic reaction
is contact dermatitis, a skin disorder. The rejection of
transplanted organs is also mediated by T cells and thus may be considered
a delayed allergic response.
Encyclopedia Britannica
Home
●
Up
●
Asthma
●
Allergy
●
Allergy Terms
●
Sinusitis
●
Sinus Problem
●
Indoor Pollution & Sinusitis |
Do-It-Best-Yourself Mold Solutions
Phil can help you fix your own property’s mold
problems at low-cost, more safely, and better-in- results than what is
done by many mold inspectors and mold contractors. How can Phil
help you?
1. Read Phil’s five plain-English,
mold advice books to master mold
inspection, testing, removal, remediation, and prevention for your house,
condo, apartment, office, or workplace.
2. Buy do-it-yourself, affordable
mold test kits,
mold lab analysis,
video inspection scope,
mold cleaner, and
mold killer, for the successful toxic and household mold
inspection, mold testing, mold species identification and quantification,
mold cleaning, mold removal, and mold remediation to find mold, kill mold,
clean mold, and remove mold from your residence or commercial building.
3. Get FREE mold advice, mold help, and/or answers
to your mold questions, by emailing mold expert Phillip Fry at
envirodangers@yahoo.com.
You can also email pictures of your mold problems in
jpeg file format as email attachments. |