<<Disclaimer: Verify this information before applying it to your situation.>>

Thanks to everyone -- all 25 of you -- who responded. The short answer (from
Heidi) is:
The classic "Allergy" is mediated by a chemical called IgE in the body. That
is, when your body senses, say, cat dander, it produces lots of IgE to fight
it. You test for IgE with a skin test. IgE allergies product runny noses,
itchy eyes, etc. and sometimes analphalytic shock.
Celiac is mediated by IgA, and it's the ONLY immune reaction I've heard
mentioned that uses IgA. There must be others!  But the IgA reaction somehow
induces the body to attack itself, which is what the term "autoimmune
disease" means. Celiac also involves IgG though.


The more technical answer is from Eileen who wrote:

There are 4 different types of allergic responses. Most food allergies and
enviornmental allergies( Cats, dust etc) are the result of inappropriate B
cell activation- specifically the IgE antibody - which then activates mast
cells, which generally cause a histamine release. When one consumes food
that one is allergic to, the allergen (or antigen) binds with the IgE
antibody that is attached to the mast cells on the gut mucosa. Histamine is
released and cramping, diarrhea results. People can get anaphylactic
allergic reactions from food allergies too- a more systemic (throughout the
body) histamine release. This is a type 1 hypersensitivity reaction.
Ceiac Disease is a type 4 hypersensitivity reaction. In this instance when
the gliadin portion of wheat proteins or the prolamin proteins in barley or
rye are consumed , the T cells of the immune system are activated which ends
up destoying the mucosa of the small intestine villi. So the major, simple
difference is that B cells (antibodies) and T cells are both important
cells in our immune system. Simple food allergies are a B cell
hypersensitivity reaction, Celiac Disease is a T cell hypersensitivity
reaction. An up-to-date immunology book would explain all of this. I can
see an old time doctor not knowing the difference because the field of
immunology is quite new and the information changes daily. I took an
immunology course last year so I could educate myself to understand
allergies and autoimmune diseases. I am an RN. I hope this helps you!

I thank you all! I know I can now explain to him why he's wrong on this
issue. Oh, and btw, he's not a GI doctor, he's in ENT but we were just
talking about CD vs. allergies.
Sally

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