In article <4754551f$0$14782$bf4948fe@[EMAIL PROTECTED]
>, WA
<WA@[EMAIL PROTECTED]
> wrote:
> Hi,
>
> Question: anyone know of scientific research on exercise induced food
> allergy in relation****p to parasites like giardia?
>
> Or, more general: allergy and parasites?
>
> Regards,
> WA
Believe it or not, the relation****p between multi-cellular parasites
(helminths) and allergies is *inverse*. The parasites secrete signals
that quell the immune system.
there is an inverse relation****p between parasitic infection (especially
worms/helminths) and allergy; as parasitic infections dropped on the
Pacific island of Mauke, allergies increased pro****tionately; one theory
is that when freed of parasitic targets, the immune system has time on
its hands and turns on innocuous allergens; the bodyıs Y-shaped IgG
antibodies usually target bacteria and viruses by latching directly on
to target proteins and recruiting immune cells; parasites activate a
different mechanism - Y-shaped IgE antibodies - which attach their tails
to the surface of mast cells; mast cells are found wherever the body
comes into contact with the outside world and thus multicellular
parasites - mucous membranes of the eyes, nose, and throat, and in the
lining of the lungs and gut; once the initial IgE response is complete,
each mast cell has 100,000 to 500,000 Y-shaped antibodies protruding
from its surface with outstretched arms; usually within two weeks of
worm infestation, the immune system is primed and each mast cell
contains a thousand or more large, globular granules; a worm protein
sticks to the arms of two adjacent IgE antibodies and sets off a
reaction causing the mast cell to burst and spew its granules (mast cell
degranulation) of histamines and other inflammatory chemicals that
infiltrate local tissues; this causes itching; blood vessels dilate and
leak; tissues swell and mucus production increases; this response may
prevent worms from infiltrating further through the skin; other cells
are attracted to dump toxins on the parasites; intestinal worms, on the
other hand, come in through the mouth and attack the GI tract; in this
case, an inflamed gut producing fluid and mucus causes in diarrheamaybe
to flush out worms before they can attach; some worms can also spend
part of their life cycle in the human lung (like schistosomiasis); this
may trigger coughing and sneezing; this responses are all more acute to
newcomers in the tropics when first exposed to parasites; some worms do
get through though mostly the system works to protect people; in the
absence of helminths, IgE antibodies can zero in on airborne allergens
(causing asthma or hayfever) or ingested foods instead; worm infested
rats have weak allergy responsesl their IgE antibodies are tied up
fighting worms; however, in rural New Guinea, worm infestation doesnıt
lessen the asthma rate; thereıs an IgG antibody that competes with IgE;
this G antibody (IgG4) grabs the worm protein before it bumps into the E
antibody attached to a mast cell and this prevents the mast cell
degranulation; IgG4 (1-2%) is the rarest of the IgGıs; IgG1 targets
viruses and bacteria and is the most common; in people with parasites;
IgG4 jumpts to 18%
<http://www.discover.com/issues/sep-93/features/ofparasitesandpo264/>
the hygiene hypothesis was advanced in 1989 by David Strachan of the
London School of Hygiene and Tropical Medicine; the immune system
expects a dirty environment and when it isnıt living in on it becomes
hyperactive; Gabonese children with worm infestations have fewer
allergies (and more IL-10, which blocks inflammatory signals among
immune cells); children treated for worms became much more sensitive to
dust mites; Alan Brown of Britain's University of Nottingham has treated
his hayfever with intestinal hookworms; they cause anemia and require
overeating; Joel Weinstock (once at the University of Iowa, now Tufts)
used pig whipworms (Trichuris suis; TSO from Ovamed) to treat ulcerative
colitis <http://www.cosmosmagazine.com/node/695>
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